Tuesday, August 23, 2011

Mineral N


 

THE MINERAL NAGYAGITE

 

  • Chemistry: AuPb(Sb, Bi)Te2 - 3S6, Gold Lead Antimony Bismuth Iron Tellurium Sulfide
  • Class: Sulfides
  • Subclass: Sulfosalts and Tellurides
  • Uses: As a very minor ore of gold and as mineral specimens.
  • Specimens

Nagyagite's chemistry is golden! Nagyagite is one of only a few minerals that are composed of gold. Gold does not often combine with other elements and seems to prefer an existance as elemental, native gold. But there are a few gold minerals and most of those are tellurides, like nagyagite. The two most common and better known gold tellurides are calaverite and sylvanite.

All three minerals are found in relative abundance at a classic gold locality; Sacaramb, Transylvania, Romania. This is the type locality for nagyagite (from where it was first described). Sacaramb was formerly named Nagyag, hence the name for nagyagite. The Sacaramb gold mines are the type localities for several rare and classic gold and silver tellurium minerals such as krennerite, muthmannite, petzite and stutzite. Nagyagite is found here and at other localities in hydrothermal veins where it forms with gold, calaverite, sylvanite and other tellurides. Nagyagite is sometimes referred to as "foliated telluride" because of its foliated crystal habits. Another name for nagyagite is "black tellurium" for its color and tellurium content.

 

PHYSICAL CHARACTERISTICS:

  • Color is a dark lead gray to black.
  • Luster is metallic.
  • Transparency: Crystals are opaque.
  • Crystal System: Orthorhombic (pseudotetragonal).
  • Crystal Habits include platy to tabular crystals as well as foliated to micaceous masses.
  • Cleavage: perfect in one direction (basal).
  • Fracture: hackly.
  • Hardness is 1 - 1.5
  • Specific Gravity is 7.4 - 7.6 (much heavier than average for metallic minerals)
  • Streak is dark gray.
  • Associated Minerals include quartz, krennerite, hessite, native gold calaverite and sylvanite.
  • Notable Occurrences include the type locality of Sacaramb (formerly Nagyag, hence the name), Transylvania, Romania as well as Kalgoorlie, Western Australia; Washburn Mine, Sunshine and Gold Hill, Boulder County, Colorado; Dorleska Mine, Trinity County and in Shasta and Calaveras Counties, California and Kings Mountain Mine, Gaston County, North Carolina, USA.
  • Best Field Indicators are crystal habit, color, softness, locality, associations and density.

 

 

 

THE MINERAL NAHCOLITE

 

  • Chemistry: NaHCO3 , Sodium Bicarbonate.
  • Class: Carbonates
  • Uses: Only as mineral specimens.
  • Specimens

Nahcolite is one of those rare minerals that are named for their chemistry. In this case, straight from its formula: NaHCO3. Simply replace the (3) with (-lite) and you get nahcolite! There are similarly named minerals such as cavansite which stands for calcium vanadium silicate; nahpoite for its formula Na2H(PO4); nacaphite for being a sodium (Na) calcium (Ca) phosphate and the inverse canaphite for calcium (Ca) sodium (Na) phosphate. The HCO3 ion in nahcolite's formula is called bicarbonate and is composed of one hydroxide which has taken the place of one of the three oxygens on a normal carbonate ion, CO3. NaHCO3 is also known chemically as "baking soda". Nahcolite forms large concretionary masses in the oil-shales of the Green River Formation and as an evaporite mineral in non-marine sedimentary deposits. Nahcolite was first discovered as a mineral at Searles Lake, California in 1940 and forms several beds in the lake sediments, some up to two feet thick. Nahcolite can absorb water and specimens should be stored in closed containers.

 

PHYSICAL CHARACTERISTICS:

  • Color is colorless, white, brown or gray.
  • Luster is vitreous.
  • Transparency: Crystals are transparent to translucent.
  • Crystal System is monoclinic; 2/m.
  • Crystal Habits include prismatic crystals, but usually massive crusts.
  • Cleavage: There is a perfect cleavage.
  • Hardness is 2.5.
  • Specific Gravity is 2.2 (well below average)
  • Streak is white.
  • Associated Minerals include other sedimentary evaporite minerals such as hanksite, gaylussite, analcime, halite, pirssonite, northupite, borax and calcite.
  • Notable Occurrences include Searles Lake, San Bernardino County and Deep Spring Lake, Inyo County, California and the Green River Formation, Colorado, USA; Egypt and Lake Magadi, Kenya.
  • Best Field Indicators: Environment of formation, cleavage, density, crystal habit and locality.

 

 

 

THE MINERAL NARSARSUKITE

 

  • Chemistry: Na2(Ti, Fe)Si4(O, F)11, Sodium Titanium Iron Silicate Fluoride.
  • Class: Silicates
  • Subclass: Inosilicates
  • Uses: Only as mineral specimens and cut as gemstones for gemstone collectors.
  • Specimens

Narsarsukite is not a well known mineral, but it is a nice collection mineral. It is named for the wonderful mineral locality at Narsarsuk, Greenland, from where the first specimens were described in 1900. The locality is the result of agpaitic pegmatite intrusions, an unusual igneous rock that is high in alkaline metals (such as sodium) and poor in silica. These intrusions also contain a large number of unusual elements such as titanium, fluorine and rare earth metals.

Narsarsukite is also found at Mont Saint-Hilaire, Quebec; another agpaitic pegmatite location. Here is probably the best location for narsarsukite specimens as crystals are relatively large and well formed.
Narsarsukite has been cut as a gemstone, although do not expect to see it available in many jewelry stores. It is cut mostly for gemstone collectors, but is considered attractive. A cut stone of 0.31 carats was cut from the mines of Mont Saint-Hilaire, Quebec and is the largest known narsarsukite gemstone.

Narsarsukite's structure involves double chains of linked silicate tetrahedrons in a tube like arrangement. The chains are actually kinked into a what is best described as a "crankshaft" shape with the kinks going up and down like a crankshaft. The chemistry of narsarsukite may include yttrium, calcium and potassium, but they are not usually significant enough to include in the general formula.

 

PHYSICAL CHARACTERISTICS:

  • Color is various shades of yellow, green, pink and brown as well as colorless.
  • Luster is vitreous or adamantine to dull or greasy.
  • Transparency: crystals are transparent to translucent.
  • Crystal System is tetragonal.
  • Crystal Habits include tabular and prismatic crystals often arranged into sprays and parallel aggregates.
  • Cleavage is perfect in two directions (prismatic) and good in one direction (basal).
  • Fracture is uneven to subconchoidal.
  • Hardness is 6 - 7.
  • Specific Gravity is approximately 2.6 to 2.8
  • Streak is white.
  • Other Characteristics: Index of refraction: 1.601 - 1.614 and 1.632 - 1.647.
  • Associated Minerals are quartz, microcline, albite, amphiboles, carletonite, lorenzenite, calcite, leucosphenite, natrolite and aegirine.
  • Notable Occurrences include the type locality at Narsarsuk, Greenland and perhaps the best source of Mont Saint-Hilaire, Quebec, Canada as well as in north-central Montana, USA.
  • Best Field Indicators: Crystal habit, cleavage, color, associations and localities.

 

 

 

THE MINERAL NATROJAROSITE

 

  • Chemistry: NaFe3(SO4)2(OH)6, Sodium Iron Sulfate Hydroxide.
  • Class: Sulfates
  • Group: Alunite
  • Uses: Only as mineral specimens.
  • Specimens

Natrojarosite is a somewhat rare sulfate mineral. It is closely related to the mineral jarosite. Jarosite is isostructural with natrojarosite which means that they have the same crystal structure but different chemistries. In this case, jarosite contains potassium instead of natrojarosite's sodium (natro is derived from the Latin for sodium, natrium, from where sodium gets its symbol, Na). The two minerals are difficult to distinguish without a chemical test.

Both minerals are isostructural with alunite with a formula of KAl3(SO4)2(OH)6, who lends its name to the Alunite Group of which all three minerals belong.

The symmetry of natrojarosite is the same as the members of the Tourmaline Group. Crystals of natrojarosite however do not form prismatic crystals like those of the typical tourmaline mineral. Natrojarosite's crystals are more flattened and resemble nearly cubic rhombohedrons. The "rhombohedrons" are actually a combination of two trigonal pyramids. Unfortunately crystals of natrojarosite are rather scarce.

 

PHYSICAL CHARACTERISTICS:

  • Color is yellow, orange or brown.
  • Luster is vitreous.
  • Transparency: Crystals are transparent to translucent.
  • Crystal System is trigonal; 3 m
  • Crystal Habits include tabular to flattened rhombohedral looking crystals. The "rhombohedrons" are actually a combination of two trigonal pyramids. Crystals are scarce, more commonly as earthy masses, films or crusts, botryoidal and granular.
  • Cleavage is good in one direction but only seen in the larger crystals.
  • Fracture is uneven.
  • Hardness is 3 - 4.
  • Specific Gravity is approximately 3.1 - 3.3 (slightly heavy for translucent minerals, but hard to obtain from crusts)
  • Streak is yellow.
  • Associated Minerals are barite, goethite, limonite, hematite and other iron minerals.
  • Notable Occurrences include Black Hills, South Dakota and Soda Springs Valley, Nevada USA; Chili; Russia; Mexico and Greece.
  • Best Field Indicators are crystal habit, associations, color and hardness.

 

 

 

THE MINERAL NATROLITE

 

Natrolite is a common and popular zeolite mineral. Its radiating sprays of ice clear acicular crystals are not exclusive to natrolite but they are a hallmark of this mineral. Natrolite can make a fine specimen in itself but it often is an accessory to other minerals and can enhance the beauty of associated minerals such as apophyllite, heulandite, benitoite and others.

Natrolite's structure has a typical zeolite openness about it that allows large ions and molecules to reside and actually move around inside the overall framework. The structure contains open channels that allow water and large ions to travel into and out of the crystal structure. The size of these channels controls the size of the molecules or ions, and therefore zeolites like natrolite can act as a chemical sieve. Natrolite's structure contains chains of silicate tetrahedrons aligned in one direction; this produces the needle-like crystals. Its cleavage results from the weaker bonds between the chains.

Natrolite, a sodium zeolite, scolecite, a calcium zeolite, and mesolite, a calcium and sodium zeolite, are closely related and sometimes found together. The presence of calcium in two of the minerals makes the structure slightly different from that of natrolite; it is altered from an orthorhombic symmetry to a monoclinic symmetry. However, the twinning of scolecite and mesolite often make them appear orthorhombic. All three minerals are referred to as "chain" or "needle" zeolites. They are similar and difficult to distinguish when in clusters with radiating, acicular habits. Natrolite tends to forms thin crystals with pyramidal terminations, but mesolite's fiber-like crystals are usually the thinnest of the three. Scolecite's larger crystals tend to be more robust and durable. These characteristics are only generalities, though, and can not be used as dependable identifying traits; absolute identification cannot be made by ordinary means.

 

PHYSICAL CHARACTERISTICS:

  • Color is clear or white; also tinted yellow and brown.
  • Luster is vitreous to dull on some compact masses.
  • Transparency: crystals are transparent to translucent.
  • Crystal System is orthorhombic; mm2
  • Crystal Habits include sprays of needle thin acicular crystals with a pyramidal termination. Also nodules, fiberous and massive crusts.
  • Cleavage is perfect in two directions, prismatic. Cleavage is rarely seen due to small crystal size.
  • Fracture is conchoidal.
  • Hardness is 5 - 5.5.
  • Specific Gravity is approximately 2.2 (very light)
  • Streak is white.
  • Associated Minerals are quartz, apophyllite, benitoite, heulandite, stilbite and other zeolites.
  • Notable Occurrences include Poona, India; San Benito, California; New Jersey and Nova Scotia.
  • Best Field Indicators are crystal habit, density and associations.

 

 

 

THE MINERAL NEALITE

 


Nealite is a very rare mineral. It was named for an American mineral collector, Neal Yedlin. Nealite is known from one locality, its type locality of Lavrio (formerly Lavrion and Laurium), Greece. Other rare minerals from this locality include paralaurionite, laurionite, ktenasite, zincaluminite, fiedlerite, penfieldite, serpierite, thorikosite, glaucocerinite, beudantite, georgiadesite and phosgenite to name just a few. This locality has been mined for centuries starting with the Greeks and then the Romans for the lead content of its ores. The left over rocks, that were judged too poor in the metals to be processed by the ancient miners, were dumped into the sea. Such mining dumps are called slag dumps. Today these dumps are being reprocessed for their valuable metals by modern ore processing techniques that are capable of extracting the metals from these ores. Analysis of these rocks have yielded some amazing new minerals. Some of these minerals were not there when the rocks were first mined centuries before. But they are there now! The sea water altered the low grade lead ores and produced a most unusual assortment of rare minerals of which nealite is one of them. Many people do not consider these minerals to be true minerals because their creation was indirectly aided by the actions of humans and therefore not exactly natural. Minerals must have a natural origin in order to be minerals. However, these minerals were only indirectly affected and the study of their origins is best left to mineralogists.

Nealite has a bright and attractive color. It is found only in microcrystals and is very hard to obtain for one's collection. But its beauty, rarity and interesting origin make it a very desirable mineral, especially for micromounters.

 

 

 

 

PHYSICAL CHARACTERISTICS:

  • Color is typically orange, also yellow.
  • Luster is vitreous.
  • Transparency: Crystals are transparent to translucent.
  • Crystal System is trigonal.
  • Crystal Habits include platy prismatic to acicular crystals with a sharp domal termination.
  • Cleavage is absent.
  • Fracture is uneven.
  • Hardness is 4
  • Specific Gravity is approximately 5.88 (well above average for translucent minerals)
  • Streak is a pale orange yellow.
  • Other Characteristics: Crystals are brittle.
  • Associated Minerals include paralaurionite, georgiadesite and other rare lead slag minerals.



    

THE MINERAL NEPHELINE

 

  • Chemistry: (Na, K)AlSiO4 , Sodium Potassium Aluminum Silicate.
  • Class: Silicates
  • Subclass: Tectosilicates
  • Group: Feldspathoid.
  • Uses: As mineral specimens and as raw material for special kinds of glass and ceramics.
  • Specimens

Nepheline is a major rock forming mineral that is not often sold in rock shops due to a lack of good crystals or attractive specimens. It is a major component of several igneous rocks called nepheline syenite, nepheline monzonite and nephelinite. The basic difference between these is in the amount and types of feldspars present. In nepheline syenite potassium feldspars or K-spars are the predominant feldspar. In the nepheline monzonite rocks both k-spars and plagioclase feldspars are present in near equal proportions. And finally in the nephelinites there is little of any of the feldspars present and the rock is mostly nepheline.

The formula of nepheline in some sources will list it as NaAlSiO4. There are very few natural nephelines that have this "pure" chemistry although it produces a stable structure and it is manufactured for use in ceramics and glass production. Potassium is always present in some amounts and often the chemical analysis of nepheline will approach Na3K(AlSiO4)4. This result reflects the fact that the alkali sites for the sodiums and potassiums have an interesting difference in the amount of space within the nepheline structure. There is actually one site out of four that is larger than the other three sites. This larger site is a more comfortable fit for the larger potassium ion.

Nepheline is a member of the feldspathoid group of minerals. Minerals whose chemistries are close to that of the alkali feldspars but are poor in silica (SiO2) content, are called feldspathoids. As a result or more correctly as a function of the fact, they are found in silica poor rocks containing other silica poor minerals and no quartz. If quartz were present when the melt was crystallizing, it would react with any feldspathoids and form a feldspar. Localities that have feldspathoids are few.

Nepheline is reactive to acids although it does not bubble like many of the carbonates. If powdered it will dissolve in hydrochloric acid and if clear specimens are dipped in acid they will become cloudy or frosted. This could be helpful in distinguishing nepheline from some similar looking feldspars, scapolite and cryolite.

The greasy luster of nepheline also is diagnostic. Massive nepheline with a greasy luster is given the variety name "eleolite" which is derived from the greek word for oil. Nepheline is derived from the greek word for cloud in allusion to its cloudy or translucent crystals and masses.

 

PHYSICAL CHARACTERISTICS:

  • Color is usually off white to gray or brown and occasionally other tints.
  • Luster is mostly greasy to dull in weathered specimens.
  • Transparency: Crystals are translucent to more rarely transparent.
  • Crystal System: Hexagonal; 6
  • Crystal Habits: Usually massive or granular. Some prismatic to columnar crystals are found with a simple hexagonal cross section.
  • Cleavage is poor, in three directions, prismatic, but rarely seen.
  • Fracture is conchoidal to uneven.
  • Hardness is 5.5 - 6
  • Specific Gravity is 2.6+ (average)
  • Streak is white.
  • Other Characteristics: Application of acids onto the surface of nepheline will cause a cloudy frosting and powdered nepheline will dissolve in hydrochloric acid.
  • Associated Minerals include calcite, feldspars such as albite, apatite, biotite, hornblende, cancrinite, sodalite and other feldspathoids.
  • Notable Occurrences include Kola Pennisula, Russia; Mt. Vesuvius, Italy; Bancroft area, Ontario, Canada and Kennebec Co., Maine, USA.
  • Best Field Indicators luster, associations, reaction to acids, locality and hardness.



 

 

THE MINERAL NEPTUNITE

 

  • Chemistry: KNa2Li(Fe, Mn)2Ti2Si8O24, Potasium Sodium Lithium Iron Manganese Titanium Silicate
  • Class: Silicates
  • Subclass: Inosilicates
  • Uses: mineral specimens.
  • Specimens

Neptunite was only discovered during this century and is of rare occurence. Its most famous specimens come from the wonderful deposits at San Benito County in California. This site contains natrolite veins in a serpentinite rock. Embedded in the pure white natrolite are the sapphire blue benitoite and the black prismatic crystals of neptunite. The assemblage is a classic among collectors and specimens with all three minerals are much sought after. Neptunite is named after the Roman god of the sea, Neptune. Crystals are well formed and typically show multiple secondary faces. The flashes of red that appear to come right from the center of the crystal are a nice added touch to this rare and interesting mineral.

 

PHYSICAL CHARACTERISTICS:

  • Color is black to reddish black.
  • Luster is vitreous.
  • Transparency crystals are translucent to opaque.
  • Crystal System is monoclinic; 2/m
  • Crystal Habits include prismatic, elongated crystals with nearly square cross-sections. The terminations are modified and slanted dome faces. Also found massive and in disseminated grains.
  • Cleavage is perfect in two direction at 80 and 100 degree angles.
  • Fracture is splintery.
  • Hardness is 5.5
  • Specific Gravity is approximately 3.23 (slightly above average)
  • Streak is reddish-brown.
  • Associated Minerals are benitoite, natrolite, serpentine, aegerine and joaquinite.
  • Other Characteristics: an internal red reflection can sometimes be seen through the prismatic crystal faces.
  • Notable Occurrences include the famous San Benito Co., California site as well as Narsarssuk Greenland and the Kola penninsula, Russia.
  • Best Field Indicators are crystal habit, internal reflection, streak, associations, color, and cleavage.




                    

THE MINERAL NICKEL

 

  • Chemistry: Ni, Elemental Nickel
  • Class: Elements
  • Group: Iron
  • Uses: as a mineral specimen and scientific studies.
  • Specimens

Native Nickel is extremely rare in nature, as it is almost always alloyed with iron. Iron meteorites, for example, are typically 6% to 20% nickel.

In 1967 native nickel was identified in samples from Bogata in New Caledonia. It forms in serpentinized ultramafic rocks from low-temperature hydrothermal activity. It has since been identified from a number of other locations, including meteor strikes.

 

PHYSICAL CHARACTERISTICS:

  • Color is bluish white.
  • Luster is metallic.
  • Transparency is opaque.
  • Crystal System is isometric
  • Crystal Habits crystal form is extremely rare; cubic when found, but generally granular or massive.
  • Cleavage is absent.
  • Fracture is hackly.
  • Streak is gray metallic.
  • Hardness is 4-5
  • Specific Gravity is 7.8-8.2 (heavy even for metallic)
  • Other Characteristics: malleable, mildly attracted to magnets.
  • Associated Minerals are olivine, pyroxenes, and some minerals that are only found in meteorites. In terrestrial samples it is found with gold and platinum and with sulfide ores.
  • Notable Occurrences New Caledonia, Meteor Crater, Arizona and San Diego County California, USA,
  • Best Field Indicators are environment, weak attraction to magnets, malleablility.



 

    

THE MINERAL NICKELINE

 


Nickeline has somewhat of an identity crisis. It is alternatively known as niccolite (mostly in Europe). Reference books often use Nickeline (Niccolite) or Niccolite (Nickeline) as a heading. The growing trend and "official" name is nickeline as is used here.

Its first name was the German term "Kupfer nickel" or copper nickel. It sounds like some sort of alloy. It actually was a term of derision because nickel meant "nixes" or underground goblins. The miners in Germany who first saw the copper-red metallic mineral were convinced the mineral was a rich ore of copper. Instead, try as they might, no copper was to be produced from the nickel arsenide. The metal that was produced from the mineral was found to be useful and valuable and it is from this unflattering term that the metal received its name, nickel (Ni).

Nickeline is also the name of a group of hexagonal minerals of which the mineral nickeline is one of the more common members. Members of the Nickeline Group have a very simple formula, namely: AX. Where the metal ion, A, is either cobalt, palladium, platinum, nickel and/or iron and the X can be either arsenic, selenium, bismuth, tellurium and/or antimony with some members having some sulfur. All members of the group have nickeline's basic structure. They are all hexagonal and except for nickeline and pyrrhotite, are very uncommon to rare in occurrence.

These are the members of the Nickeline Group:
  • Breithauptite (Nickel Antimonide)
  • Freboldite (Cobalt Selenide)
  • Imgreite (Nickel Telluride)
  • Langistite (Cobalt Nickel Arsenide)
  • Nickeline (Nickel Arsenide)
  • Pyrrhotite (Iron Sulfide)
  • Sederholmite (Nickel Selenide)
  • Stumpflite (Platinum Antimonide Bismuthinide)
  • Sudburyite (Palladium Nickel Antimonide)

Niggliite (Platinum tin), was a member of this group and shares the same structure but is considered an alloy, having metallic bonds instead of ionic bonds.

Pyrrhotite has hexagonal and monoclinic components. The hexagonal components are placed in the Nickeline Group, but most natural pyrrhotite is a mixture of both components.

Nickeline's structure is fairly simple with the nickel ions, in hexagonal packing, forming stacked identical layers parallel to the major six-fold axis. The arsenic ions rest between the nickel ion layers, but in a staggered or alternating sequence such that the next layer is not in the same position as the previous layer. Each metal ion is surrounded by six arsenics; three below and three above. The major axis is actually a six-fold screw axis (helix) about the nickel ions.
A screw axis is an axis that has a rotation and a translation in the major axis direction. So, in this case, the axis will start with an arsenic ion at the base level. A rotation about the axis of 60 degrees and then movement (approximately 2.5 angstroms) along the axis produces the next arsenic ion. If this is done a total of six times, then the entire structure and consequently the symmetry of nickeline is reproduced. All members of the Nickeline Group share this basic structure, but with their own combination of elements of course.

Nickeline is not exactly a common mineral, but is found with other nickel and cobalt sulfide ores and thus it is included with them when mined for their various ores. This makes nickeline a minor ore of nickel and commercially important is some localities. The sulfides are usually hydrothermal in origin, although nickeline is also found in basic igneous rocks such as gabbros. Although crystals of nickeline are very scarce, some formations of nickeline can be attractive and an interesting addition to someone's collection.

 

PHYSICAL CHARACTERISTICS:

  • Color is copper-red to pink.
  • Luster is metallic.
  • Transparency: Crystals are opaque.
  • Crystal System: Hexagonal; 6/m 2/m 2/m
  • Crystal Habits are limited to mostly massive and granular components of massive hydrothermal sulfide rocks and gabbros, but a few localities have produced good pyramidal or tabular crystals. Columnar and reniform habits are also seen. Rare fourling twins are also seen.
  • Cleavage: Not observed.
  • Fracture: Uneven.
  • Hardness is 5 - 5.5
  • Specific Gravity is approximately 7.8 (well above average for metallic minerals)
  • Streak: Dark brown to black.
  • Other Characteristics: Will often develop a dark tarnish on fresh surfaces and weathered surfaces may have a coating of the green nickel arsenate, annabergite. Upon heating a garlic odor maybe observed due to the arsenic content. Crystals tend to be striated.
  • Associated Minerals include arsenopyrite, barite, silver, annabergite, cobaltite, pyrrhotite, pentlandite, chalcopyrite, breithauptite and maucherite.
  • Notable Occurrences include the Natsume nickel mine, Japan and at Mansfeld and Eisleben, Germany; Franklin, New Jersey; California and Colorado, USA; Styria, Austria; Sinaloa, Mexico; Talmessi, Anarak, Iran and at Great Slave Lake, Northwest Territories, Canada; Cobalt and Sudbury, Ontario, Canada as well as some sites in England, France, Morocco, Russia and southern Australia.

         

THE MINERAL NITER

 


Niter is one of the few nitrate minerals that is available on the mineral markets. Nitrates are not all that commonly found due to their general ease in dissolving in water. In fact some solid nitrate crystals will even become liquid by removing water from the moisture in the air, a process called deliquescence. Niter however is not deliquescent, but still is very soluble in water. Most nitrates are found in arid, desert regions such as around the Persian Gulf or found as efflorescences on dry cave or mine walls.

Nitrates are similar to carbonates. The nitrogen is surrounded by three oxygens and forms a tight flat triangular NO3 ion group just like the carbonate triangular CO3 ion group. Thus nitrates are placed in the Carbonate Class of minerals.

But there are some differences. The nitrogen has a higher charge (+5) and is smaller than the carbon (+4) and thus the nitrogen holds the oxygens a lot closer and the nitrogen oxygen bonds are stronger. Also the overall charge of the nitrate ion group is only negative one (-1) compared to the carbonate's ion group's charge of negative two (-2). These differences show up in a greater difficulty in breaking apart the nitrate ion group as is usually an easy task for acids with the carbonate ion group, greater solubility and a much less diverse subclass of minerals.

Niter is most similar to the orthorhombic carbonates or those carbonates that belong to the Aragonite Group, specifically aragonite, witherite, strontianite and cerussite. The structures of niter and the members of the Aragonite Group are analogous and they therefore share many similar properties such as symmetry and crystal habits.

Another nitrate called nitratine, NaNO3 (also known as "soda niter") is structurally more similar to the Calcite Group of carbonate minerals. Nitratine in appearance is similar to niter but is deliquescent and gives a different result in a flame test. The flame test is where a sample is burned in a flame and gives off a certain color. For niter the flame should be violet, an indicator of potassium, and for nitratine the flame should be yellow, an indicator of sodium.

Niter, specifically KNO3, is also known as "saltpeter" which is said to reduce the sexual desire in humans, especially males. Kind of a reverse aphrodisiac. Ironically, it is also used as a fertilizer.
 
PHYSICAL CHARACTERISTICS:
  • Color is white or gray, also tinted yellow or brown by impurities.
  • Luster is vitreous.
  • Transparency Crystals are translucent to transparent only in individual crystals.
  • Crystal System is orthorhombic; 2/m 2/m 2/m
  • Crystal Habits include crusts and acicular crystals formed as efflorescence on cave and mine walls. Also as a constituent in arid climate soils. Rarely forms crystals of any appreciable size but some clusters of hexagonal shaped twinned crystals are known.
  • Cleavage is good in two directions (prismatic).
  • Fracture is uneven.
  • Hardness is 2.
  • Specific Gravity is approximately 2.1 (well below average)
  • Streak is white.
  • Other Characteristics: Easily soluble in water, gives a violet flame in a flame test (potassium), is slightly sectile and is nondeliquescent.
  • Associated Minerals calcite, dolomite and certain minerals in various arid region soils.
  • Notable Occurrences include the Persian Gulf states, India; Russia; Italy; Spain; northern Chile; New Mexico, Kentucky and Tennessee, USA; Egypt and Bolivia.
  • Best Field Indicators are crystal habit if visible, solubility in water, nondeliquescent and violet flame test.

 

 

THE MINERAL NITRATINE OR SODA NITER

 

  • Chemistry: NaNO3, Sodium Nitrate
  • Class: Carbonates
  • Subclass: Nitrates
  • Uses: as a source of nitrate for fertilizer and as mineral specimens.
  • Specimens

Nitratine or soda niter is one of the few nitrate minerals that is available on the mineral markets. Nitrates are not all that commonly found due to their general ease in dissolving in water. In fact some solid nitrate crystals will even become liquid by removing water from the moisture in the air, a process called deliquescence. Nitratine is deliquescent and is very soluble in water and thus care should be taken to preserve valuable specimens in air tight containers with desiccant. Most nitrates are found in arid, desert regions such as around the Persian Gulf or found as efflorescences on dry cave or mine walls.

Nitrates are similar to carbonates. The nitrogen is surrounded by three oxygens and forms a tight flat triangular NO3 ion group just like the carbonate triangular CO3 ion group. Thus nitrates are placed in the Carbonate Class of minerals.
But there are some differences. The nitrogen has a higher charge (+5) and is smaller than the carbon (+4) and thus the nitrogen holds the oxygens a lot closer and the nitrogen oxygen bonds are stronger. Also the overall charge of the nitrate ion group is only negative one (-1) compared to the carbonate's ion group's charge of negative two (-2). These differences show up in a greater difficulty in breaking apart the nitrate ion group as is usually an easy task for acids with the carbonate ion group, greater solubility and a much less diverse subclass of minerals.

Nitratine is most similar to the trigonal carbonates or those carbonates that belong to the Calcite Group, specifically magnesite, rhodochrosite, siderite, smithsonite, sphaerocobaltite and of course calcite and some rarer members. The structures of nitratine and the members of the Calcite Group are analogous and they therefore share many similar properties such as symmetry and crystal habits. The structures are so similar that nitratine in a laboratory can grow onto a crystal of calcite and essentially finish the crystal with nitratine instead calcite.

Another nitrate called niter, KNO3 (also known as "saltpeter") is more similar to the Aragonite Group of carbonate minerals. Nitratine is similar to its rarer cousin niter but is deliquescent and gives a different result in a flame test. The flame test is where a sample is burned in a flame and gives off a certain color. For niter the flame should be violet, an indicator of potassium, and for nitratine the flame should be yellow, an indicator of sodium.

Nitratine was an important source of nitrates for fertilizer and other chemical uses including fireworks. Nowadays, fixed nitrogen from the air has all but replaced nitratine as the main source of nitrogen. An interesting side note is that discarded specimens of nitratine were said to have been thrown into a garden and this is how the importance of nitrates in good plant growth was first discovered.
 
PHYSICAL CHARACTERISTICS:
  • Color is white or gray, sometimes with tints of red-brown or yellow.
  • Luster is vitreous.
  • Transparency crystals are translucent to transparent.
  • Crystal System is trigonal; bar 3 2/m
  • Crystal Habits include masses and soil deposits in arid and desert regions. Crystals are rare, but when found are in the form of rhombohedrons similar to calcite's crystals.
  • Cleavage is perfect in three directions forming rhombohedrons.
  • Fracture is conchoidal.
  • Hardness is 1.5 - 2.
  • Specific Gravity is approximately 2.2 - 2.3 (below average)
  • Streak is white.
  • Associated Minerals gypsum, halite and other arid region minerals.
  • Other Characteristics: Deliquescent, slightly sectile, very soluble in water and gives a yellow flame test result.
  • Notable Occurrences include the Tarapaca and other northern Chile sites; Bolivia; Peru and Humboldt Co., Nevada, San Bernardino Co., California and New Mexico, USA.
  • Best Field Indicators are crystal habit, flame test, solubility, deliquescence, hardness, occurrence and cleavage.

 

 

THE MINERAL NORBERGITE

 


Norbergite is one of several rare yet collectable minerals from the famous mines at Franklin, New Jersey. It is one of the many minerals there that are fluorescent. Norbergite will glow a tan to yellow color when subjected to shortwave UV light. Norbergite is often associated with other fluorescing minerals such as blue fluorescing diopside and red fluorescing calcite. The combination of different fluorescing colors can be quite attractive. Norbergite was first discovered in Norberg, Sweden from where it gets it name. It forms as small grains in the marbles of contact metamorphic environments.

Norbergite is a member of the Humite Group of minerals. Members of the Humite Group are noted for having a mixture of silicate layers and oxide layers in their structures. The silicate layers have the same structure as olivine. The oxide layers have the same structure as brucite. Norbergite is the only member of the group with just one olivine layer which alternates with the brucite layer. The formula could be written as:
Mg2SiO4 - Mg(F, OH)2

This formula distinguishes the chemistry of the two layers. The most common member of the Humite Group is chondrodite which has two olivine layers between each brucite layer. Humite, the namesake of the group, has three.

 

PHYSICAL CHARACTERISTICS:

  • Color is white, yellow, tan, brown, orange or red.
  • Luster is vitreous to resinous.
  • Transparency: Crystals are transparent to translucent.
  • Crystal System: Orthorhombic; 2/m 2/m 2/m
  • Crystal Habits include small prismatic to rounded crystals, but as is most commonly the case, as embedded indistinct grains.
  • Cleavage is poor in one direction, basal.
  • Fracture is subconchoidal.
  • Hardness is 6 - 6.5.
  • Specific Gravity is 3.1 - 3.2
  • Streak is white.
  • Other Characteristics: Many specimens (usually those that are of a lighter color) fluoresce a tan to yellow color under shortwave UV light.
  • Associated Minerals include franklinite, fluorite, pyrrhotite, spinel, tremolite, diopside, dollaseite-(Ce), chondrodite and calcite.
  • Notable Occurrences include the type locality of Ostanmosoa Iron Mine, Norberg, Vastmanland, Sweden (hence the name) as well as Franklin, New Jersey, USA; Kazabazua, Quebec and Bancroft, Ontario, Canada; Pargas, Finland and Mt. Vesuvius, Italy.
  • Best Field Indicators are color, associations, fluorescence, environment of formation and hardness.
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