Mineral W

The Mineral WALPURGITE

• Chemistry: (BiO)₄UO₂(AsO₄)₂ - H₂O , Hydrated Bismuth Uranyl Arsenate Oxide
• Class: Phosphates
• Subclass: Arsenates
• Uses: A very minor ore of uranium and bismuth and as mineral specimens.
• Specimens

Walpurgite is a chemical oddball of a mineral. Not only does it have arsenic and uranium in its chemistry, but bismuth too! The bismuth in walpurgite gives this mineral its unusually high density (SG=5.9) and luster (adamantine). It is too rare to really be considered an ore of either uranium or bismuth, but no doubt some walpurgite has gone into the processing with other ores.

Walpurgite specimens can have attractive tiny clusters of bladed radiating crystals. The mineral gets its name from the Walpurgis Vein at its type locality, Weisser Hirsh Mine, Schneeberg, Saxony, Germany. Remember, this is a radioactive mineral and should be stored away from other minerals that are affected by radioactivity and human exposure should always be limited.

PHYSICAL CHARACTERISTICS:

• Color is typically yellow but can be a reddish orange.
• Luster is adamantine to greasy.
• Transparency: Crystals are translucent to rarely transparent.
• Crystal System is trigonal.
• Crystal Habits include platy elongated crystals often aggregated and twinned. Also as crusts, fibrous and earthy.
• Cleavage is perfect.
• Fracture is lamellar.
• Hardness is 3.5
• Specific Gravity is approximately 5.95 - 6.69 (well above average for translucent minerals)
• Streak is a pale yellow.
• Other Characteristics: Radioactive, non-fluorescent and cleavage sheets are surprisingly brittle.
• Associated Minerals include bismutite, torbernite, zeunerite, uraninite and other uranium minerals.
• Notable Occurences include the type locality of Weisser Hirsch Mine, Schneeberg, Saxony, Germany also at the Miracle Mine, Kern County, California, USA.
• Best Field Indicators are color, crystal habit, high density, non-fluorescence, radioactivity and associations.

THE MINERAL WARDITE

• Chemistry: NaAl₃(PO₄)₂(OH)₄-2H₂O, Hydrated Sodium Aluminum Phosphate Hydroxide.
• Class: Phosphates
• Uses: Only as mineral specimens
• Specimens

Wardite is a poorly known mineral, but of special interest to minerologists. It is a mineral that belongs to a unique symmetry class. It is one of only a few minerals that is known to belong to the tetragonal trapezohedral class. This class has only a 4 fold rotational axis and two 2 fold rotational axes and nothing else. Crystals of wardite show the lower symmetry by displaying squashed psuedo-octahedrons with striated faces. Another tetragonal mineral that forms similar pseudo-octahedrons is the mineral scheelite. Scheelite is also a low symmetry tetragonal mineral, but belongs to a different symmetry class than wardite. However, scheelite does form similar pseudo-octahedrons, but is fluorescent and generally yellow to orange in color.

Crystals of wardite can make nice specimens with their colorless or light green color and glassy luster. Massive green wardite is associated with variscite nodules in Utah, where it formed from the alteration of the variscite. For those interested in the symmetry of minerals and rare phosphates, wardite is a "must have" in their collections.

PHYSICAL CHARACTERISTICS:

• Color is green to bluish green or white to colorless.
• Luster is vitreous.
• Transparency: Specimens are transparent to translucent.
• Crystal System: is tetragonal; 4 2 2
• Crystal Habits include the typical tetragonal dipyramids that has a distorted octahedral look (pseudo-octahedral). Found as linings in variscite nodules. Also granular, massive and fibrous crusts.
• Cleavage is good in one direction, basal.
• Fracture is conchoidal.
• Hardness is 5.
• Specific Gravity is approximately 2.8 (average for translucent minerals)
• Streak is white.
• Other Characteristics: Crystals are striated perpendicular to the four fold axis and is non-fluorescent.
• Associated Minerals are quartz, feldspars, lazulite, amblygonite, variscite and crandallite.
• Notable Occurances: include Farifield, Utah; San Diego Co, California; Taquaral, Minas Gerias, Brazil; Alaska, USA and Rapid Creek, Yukon Territory, Canada.
• Best Field Indicators: color, crystal habits, associations, striations, non-fluorescence and locality.

 

     THE MINERAL WAVELLITE

• Chemistry: Al3(PO4)2(OH)3-(H2O)5, Hydrated Aluminum Phosphate Hydroxide
• Class: Phosphates
• Uses: only as mineral specimens
• Specimens

Wavellite is a mineral that demonstrates the classic radiating globule crystal habit. In fact, you could say that wavellite is the type mineral for this habit. The habit produces a unique effect when the globules are imbedded in limestone and chert. If the rock is fractured and some of the globules are cleaved through, then a nice radial cluster is seen. The radial cluster will then reflect light to produce a sparkling pinwheel effect. Although broken mineral specimens are generally not valued by collectors, the radial play of light can be rather pretty and makes for interesting specimens. Although, a serious collector might not admit it, the more valuable specimens are those that are predominantly pristine, uncleaved clusters with at least a few cleaved globules to demonstrate the light play.

PHYSICAL CHARACTERISTICS:

• Color is characteristically green but also white, colorless, yellow and brown.
• Luster is vitreous.
• Transparency crystals are transparent to translucent.
• Crystal System is orthorhombic; 2/m 2/m 2/m
• Crystal Habit is almost exclusively radiating acicular crystals forming globules or botryoidal masses.
• Cleavage is perfect in two directions.
• Fracture is uneven.
• Hardness is 3.5 - 4.
• Specific Gravity is approximately 2.3+ (light even for translucent minerals)
• Streak is white.
• Associated Minerals are quartz, micas, turquoise and limonite.
• Other Characteristics: surface of globules often have minute crystals giving off tiny sparkles.
• Notable Occurances include Arkansas and Pennsylvania, USA; Bolivia and England.
• Best Field Indicators are crystal habit, green color and softness.

      THE MINERAL WELOGANITE

• Chemistry: Na2(Sr, Ca)3Zr(CO3)6 - 3 H2O, Hydrated Sodium Strontium Calcium Zirconium Carbonate.
• Class: Carbonates
• Uses: Only as mineral specimens.
• Specimens

Weloganite is a rare carbonate mineral. It was found at only one site that produced good crystals, the famous Francon Quarry near the city of Montreal, Quebec, Canada. The quarry has now been reclaimed as a landfill and is not producing any new specimens, making existing specimens true classics. The mineral is named for a famous geologist, the founder of Canada's Geological Survey, W. E. Logan.

The Francon quarry exposes a rare carbonatite sill. The sill, a horizontal intrusion into parallel host rocks, is composed of carbonate minerals, mostly calcite. The Francon Quarry has produced a number of rare carbonate minerals besides weloganite such as strontianite and dawsonite. Carbonatite is an igneous rock and is not all that well understood by geologists.

Like other igneous rocks, the carbonatite starts as a molten body, but is composed of carbonates instead of silicates. Like other igneous rocks, carbonatites will crystallize the minerals that are more stable at higher temperatures and pressures first, leaving difficult elements in the left over melt. Difficult elements are those elements that because of their size and/or charge do not fit well into a mineral's structure and are therefore excluded by most minerals. These elements, like strontium and zirconium, are left to form whatever minerals they can get into as the last bit of crystallization takes place.

In the case of weloganite, the sill had already formed most of its minerals when fluids rich in difficult elements and volatile gases rose to the top of the sill and formed bubbles or pockets. When the excavations at the Francon Quarry uncovered the sill, these "petrified" bubbles were found coated in exotic minerals some of which were never before known to science. It is believed that this unusual sill was somehow allowed to cool much more slowly than other carbonatite sills. It is the time to differentiate the difficult elements that may have made the difference in producing these wonderful minerals. Other carbonatite sills have similar chemistries to the Francon Quarry sill but the difficult elements are incorporated into commoner minerals as trace elements.

Weloganite forms attached crystals that grow into tapered pseudohexagonal prisms. The crystals are occasionally complexly tapered, growing wider and thinner several times before terminating to either a point or a flat pedial face. The color can be a muted amber color and can enhance these already interesting, rare and classic crystals.

PHYSICAL CHARACTERISTICS:

• Color is white, yellowish or amber.
• Luster is vitreous to chalky.
• Transparency crystals are translucent, rarely transparent.
• Crystal System is triclinic; bar 1
• Crystal Habits include pseudohexagonal prisms that often tapper to a point or are terminated by a pedial face. From their attachment points the crystals will usually taper to a wider width before tapering to their terminations or repeatedly tapering wider and thinner before terminating.
• Hardness is 4
• Specific Gravity is 3.2 (slightly above average for transparent minerals)
• Cleavage is distinct in one direction.
• Fracture is conchoidal.
• Streak is white.
• Other Characteristics: heavily striated or repeatedly notched vertically.
• Associated Minerals include strontianite, dawsonite and calcite.
• Notable Occurrences include Francon Quarry, Montreal, Quebec, Canada and only at a few other rare locations.
• Best Field Indicators are locality, crystal habit, striations and color.

THE MINERAL WHEWELLITE

• Chemistry: CaC2O4 - H2O, Hydrated Calcium Oxalate.
• Class: Organic Minerals
• Uses: Only as mineral specimens.
• Specimens

Whewellite is possibly the best known of the crystalline organic minerals. Amber, which is quite well known, is often placed in the Organic Minerals Class, but it lacks a crystalline structure. Some mineral purists might not agree that whewellite is a mineral at all as they tend to dislike any organic connection to minerals (see annapaite). In the example of whewellite, not only is there a connection but organic chemicals are right in the formula! As long as one can ignore the organic chemical connection, whewellite is its own mineral because it is naturally formed, a crystalline solid (repetitive), formed with no direct biological connection and composed of a set chemical formula.

Whewellite is the salt of oxalic acid (also known as ethanedoic acid). The formula for oxalic acid is H2C2O4. The calcium in whewellite has replaced the hydrogens in the oxalic acid by the following reaction with calcium hydroxide:

H2C2O4 + Ca(OH)2 -----> CaC2O4 - H2O + H2O

This reaction produces molecules of hydrated calcium oxalate (whewellite if in crystalline form) and water. The oxalic acid is a fairly stable molecule as organic chemicals go and the calcium hydroxide can be produced in basic ground water or in hydrothermal fluids. So all that is needed is a source of oxalic acid to produce the mineral whewellite. The source is undoubtedly organic and can come from coal or organic debris in sedimentary rocks. In deed, whewellite is found in some coal seams and sedimentary nodules and concretions. In has also been found in some hydrothermal veins (source of the oxalic acid is uncertain) and even forms upon dead agave plants in Arizona's southwestern deserts. In the later occurrence whewellite would certainly not be considered a mineral due to its most non-geological origin but the other occurrences are all up for debate.

PHYSICAL CHARACTERISTICS:

• Color is colorless, white, yellow or brown.
• Luster is vitreous to pearly.
• Transparency crystals are transparent to translucent.
• Crystal System is monoclinic.
• Crystal Habits include tiny acicular crystals and crusts. Specimens are found in hydrothermal veins, coal seams and in sedimentary nodules.
• Hardness is 2.5 - 3
• Specific Gravity is 2.2 (well below average)
• Streak is white.
• Other Characteristics:It is insoluble in water.
• Notable Occurrences include Havre, Montana; San Juan County, Utah and Arizona, USA; Zwickau and Burgk, Germany; Alsace, France and Russia.
• Best Field Indicators are crystal habit, very low density, environment of formation and locality.

 

           THE MINERAL WHITEITE

• Chemistry: (Ca, Fe, Mn)2Mg2Al2(PO4)4(OH)2 - 8H2O, Hydrated Calcium Iron Manganese Magnesium Aluminum Phosphate Hydroxide.
• Class: Phosphates
• Group: Whiteite
• Uses: Only as mineral specimens.
• Specimens

Whiteite is actually a series of minerals that have the same structure but different amounts of certain elements. They are given the rather pragmatic although not imaginative names of whiteite-(CaFeMg), whiteite-(CaMnMg) and whiteite-(MnFeMg). Whiteite-(CaFeMg)'s formula is Ca(Fe, Mn)Mg2Al2(PO4)4(OH)2 - 8H2O. Whiteite-(CaMnMg)'s formula is CaMnMg2Al2(PO4)4(OH)2 - 8H2O. Whiteite-(MnFeMg)'s formula is MnFeMg2Al2(PO4)4(OH)2 - 8H2O. The three mineral's properties are similar and most mineral guides, if they have whiteite at all, will refer to all of them simply as whiteite, as is done here. All are relatively rare phosphate minerals that form from hydrothermal precipitation and hydrothermal alteration of phosphate rich pegmatites.

PHYSICAL CHARACTERISTICS:

• Color is brown, tan, yellow, greenish-yellow, pink to lavender.
• Luster is vitreous.
• Transparency: Crystals are transparent to translucent.
• Crystal System is Monoclinic; 2/m
• Crystal Habits include tabular to stubby prismatic crystals with a rough surface being common.
• Cleavage is perfect in one direction.
• Fracture is uneven.
• Hardness is 4
• Specific Gravity is approximately 2.6 (average for translucent minerals)
• Streak is white.
• Associated Minerals include kulanite, lazulite and siderite among others.
• Notable Occurrences include Rapid Creek, Yukon Territory, Canada and Custer, South Dakota.
• Best Field Indicators are color, locality and crystal habit.

 

    THE MINERAL WHITLOCKITE

• Chemistry: Ca₉(Mg, Fe)(PO₄)₆PO₃OH, Calcium Magnesium Iron Phosphate Hydroxide.
• Class: Phosphates
• Uses: Only as mineral specimens.
• Specimens

Whitlockite is a rare phosphate mineral. It was first discovered at the famous phosphate locality - the Palermo Mine, North Groton, Grafton Co., New Hampshire. It can form small, but distinct and well formed crystals.

PHYSICAL CHARACTERISTICS:

• Color is gray, yellowish, white or colorless.
• Luster is vitreous.
• Transparency: specimens are transparent to translucent.
• Crystal System: is trigonal; 3 m
• Crystal Habits include rhombohedral and tabular crystals.
• Cleavage is absent.
• Fracture is uneven.
• Hardness is 5.
• Specific Gravity is approximately 3.1 (average for translucent minerals)
• Streak is white.
• Associated Minerals include calcite, montgomeryite, mitridatite, luecophosphite and other phosphate minerals.
• Notable Occurrences include the type locality of Palermo Mine, North Groton, Grafton Co., New Hampshire, USA as well as Rapid Springs, Yukon, Canada; Spring Creek mine, Flinders Range, Australia and the Tip Top Pegmatite, Custer Co., South Dakota, USA.
• Best Field Indicators: crystal habit, hardness, color and localities.

 

 

THE MINERAL WILLEMITE

• Chemistry: Zn2SiO4, Zinc Silicate.
• Class: Silicates
• Subclass: Nesosilicates
• Group: Phenakite
• Uses: a minor ore of zinc and as mineral specimens.
• Specimens

Willemite is a somewhat rare zinc mineral, but it was found in such great abundance at Franklin New Jersey that it instantly became an important ore of zinc. The deposit at Franklin, New Jersey is truly unique. Not only is willemite found there but other rare minerals are also found there, and some in amazingly large quantities. Minerals such as zincite, franklinite (named after the locality), rhodonite, greenockite, fluorescent calcite, various zeolites and many other rare and interesting minerals are found at this amazing locality. The unique mineral assemblage is believed to have come into existance from the metamorphism of formerly oceanic floor, metallic mineral deposits that were oxidized into secondary minerals before metamorphism. In the case of willemite the secondary minerals were probably smithsonite and hemimorphite. At other localities for willemite it is more scarce and forms as a secondary mineral from primary zinc deposits.

Dispite being discovered at Franklin first, it was a site in Belgium, where the mineral formed small brown crystals, that gave it its name, willemite. It seems that the minerologists at Franklin described the mineral but never named it. In the meantime the minerologists at Belgium named the mineral after William I of Belgium.

Willemite is one of the few silicate minerals that have a trigonal symmetry. This symmetry is far more common among carbonates than among silicates. Willemite shares the same symmetry with the emerald green silicate dioptase and the closely related silicate phenakite. Although massive willemite is much more common, some crystals do show the rhombohedral terminations atop hexagonal prisms that is characteristic of it symmetry.

Willemite's great desirability is not so much its use as a zinc ore, its rarity, its associations or even its crystal habits as it is its wonderful fluorescence. Nearly all willemite specimens fluoresce a bright green under ultra-violet light. This fluorescence combined with the red fluorescence of the calcite at Franklin, makes specimens from there even more special. Some willemite specimens will even show phosphorescence. Phosphorescence is the ability of a mineral to glow after the initial light is removed. The mineral has essentially stored the energy of the initial activating light and re-emits light on a delayed basis. Willemite is one of the best examples of a fluorescent mineral and is a must have for any collector interested in this phenomenon.

PHYSICAL CHARACTERISTICS:

• Color is usually colorless or white but can be tinted yellow, blue, red, brown and often green.
• Luster is vitreous to resinous.
• Transparency crystals are transparent to translucent.
• Crystal System: trigonal; bar 3
• Crystal Habits include typically short prismatic crystals although some prismatic crystals can be rather long with sometimes very steep rhombohedral terminations. Also as granular, lamellar and fibrous masses.
• Cleavage in good in one direction (basal)
• Fracture is conchoidal to uneven.
• Hardness is 5.5
• Specific Gravity is approximately 3.9 - 4.2 (above average for non-metallic minerals).
• Streak is white.
• Other Characteristics: strongly fluorescent green and sometimes phosphorescent.
• Associated Minerals are zincite, franklinite, rhodonite, calcite, greenockite and other rare minerals.
• Notable Occurrences include of course Franklin as well as Paterson and Sterling Hill, New Jersey and Mammoth Mine, Tiger, Arizona, USA; Morsnet, Belgium; St. Hilaire, Quebec; Tsumeb, Namibia and Greenland.
• Best Field Indicators are fluorescence, associations, luster, cleavage and crystal habit.

 

The Mineral WITHERITE

• Chemistry: BaCO3, Barium Carbonate
• Class: Carbonates
• Group: Aragonite
• Uses: a minor ore of barium and as mineral specimens.
• Specimens

Witherite is an uncommon carbonate mineral, although it is the second most common barium mineral next to the barium sulfate mineral, barite. All members of the aragonite group of minerals can form twins, but witherite is one member that always forms twins!

Twinning is the result of an error during the growth of the crystal. It occurs when the atomic layer stacking, ABCABCABCABC etc, makes a mistake and a C layer instead of a B layer is place next to an A layer. The result is an ABCABCACBACBACBA stacking. Where the mistake occurs, a mirror plane is produced. If this occurs another time, forming three twins, that are joined in a circle, then a trilling is created. The symmetry of the crystal will appear hexagonal but is still orthorhombic. These crystals can be thought of as a "triple siamese twin" where one crystal takes up one third (or 120 degrees) of the hexagon. Witherite's twins are typically capped with a six sided pyramid and often are dipyramidal.

Witherite is an interesting and valuable collection specimen that anyone, especially a collector of twinned minerals, would love to own.

PHYSICAL CHARACTERISTICS:

• Color is white, colorless, gray, brown, yellowish or greenish.
• Luster is vitreous to dull.
• Transparency crystals are transparent to usually translucent.
• Crystal System is orthorhombic; 2/m 2/m 2/m
• Crystal Habits include a pseudo-hexagonal trilling twin which forms a six-sided prism, usually with a slanted, tapering pyramid. Often they are dipyramidal without any prism faces. The faces are usually striated perpendicularly. Also there are botryoidal, massive and fibrous forms.
• Hardness is 3 - 3.5.
• Specific Gravity is 4.3+ (heavy for transparent minerals)
• Cleavage is distinct in one direction, but not usually seen due to twinning.
• Fracture is uneven.
• Streak is white.
• Associated Minerals include fluorite, celestite, galena, barite, calcite and aragonite.
• Other Characteristics: effervesces in dilute HCl solutions, also fluoresces light blue under both long and short-wave UV light and is phosphorescent under short-wave UV light.
• Notable Occurrences include Cave-in-rock, Rosiclare, Illinois, USA; Alston Moor, Cumberland and Durham, England; Thunder Bay area, Ontario, Canada and Germany.
• Best Field Indicators are twinned habits, reaction to acid, fluorescence and phosphorescent under short-wave UV light and density.

 

    THE MINERAL WOLFEITE

• Chemistry: (Fe, Mn)2PO4OH, Iron Manganese Phosphate Hydroxide
• Class: Phosphates
• Uses: Mineral specimens.
• Specimens

Wolfeite is a rare and obscure mineral. It is found in altered granite pegmatites with other rare phosphate minerals. It is important to note that the iron and manganese ions in wolfeite are in the positive two (+2) oxidation state. This is a reduced state from most altered iron and manganese minerals that contain these ions in the positive three (+3) oxidation state. This is important because the presence of wolfeite indicates that the iron and manganese have not undergone extensive oxidation. Wolfeite may be an intermediate between minerals such as hornblende which contains iron at a positive two state and higher oxidized phosphates such as purpurite. Wolfeite, whose name could easily be confused with both wolframite and wulfenite is a nice rare mineral with a rather high luster and interesting color that any collector would love to own.

PHYSICAL CHARACTERISTICS:

• Color is reddish to dark brown.
• Luster is vitreous to adamantine or even greasy.
• Transparency crystals are rarely transparent, but more commonly translucent.
• Crystal System is monoclinic; 2/m
• Crystal Habit is generally prismatic crystals or fibrous aggregates.
• Cleavage is absent.
• Fracture is uneven.
• Hardness is 4.5 - 5
• Specific Gravity is approximately 3.8+ (above average)
• Streak is white.
• Other Characteristics: Crystals are striated vertically.
• Associated Minerals include quartz, feldspars, purpurite, hureaulite, dicksonite and other phosphates found in altered granite pegmatites.
• Notable Occurrences include Custer Co., South Dakota and Palermo Mine, New Hampshire, USA and Bavaria, Germany.
• Best Field Indicators are color, crystal habit, striations, associations and luster.

 

THE MINERAL WOLFRAMITE

• Chemistry: (Fe, Mn)WO4, Iron manganese tungstate
• Class: Sulfates
• Subclass: Tungstates
• Uses: an ore of tungsten (an important industrial element) and as a mineral specimen
• Specimens

Wolframite is actually a series between two minerals; Huebnerite and Ferberite. Huebnerite is the Manganese rich end member while ferberite is the iron rich end member. Wolframite is the name of the series and the name applied to indistinguishable specimens and specimens intermediate between the two end members. Most specimens found in nature fall within 20 - 80% range of the series and these are termed wolframites. Only if they are more pure than 80% manganese are they called huebnerite and conversely if they are 80% iron they are called ferberite.

PHYSICAL CHARACTERISTICS:

• Color is Black to grey or brown.
• Luster is submetallic to resinous.
• Transparency crystals are translucent to opaque.
• Crystal System is monoclinic; 2/m
• Crystal Habits include the flat, heavily modified, tabular crystals. The crystals are elongated along the c axis and are generally flattened in the a axis direction. Also as columnar aggregates and lamellar masses.
• Cleavage is perfect in one direction parallel to the a and c axes.
• Fracture is uneven.
• Hardness is 4 - 4.5.
• Specific Gravity is approximately 7.0 - 7.5 (heavy even for metallic minerals)
• Streak is brown to black.
• Associated Minerals are quartz, hematite, tourmalines, cassiterite, micas and pyrite.
• Other Characteristics: crystals striated lengthwise.
• Notable Occurrences include Nanling Range, China; southwest and Colorado, USA; Russia; Korea; England and Bolivia.
• Best Field Indicators are crystal habit, color, density, luster and cleavage.

THE MINERAL WOLLASTONITE

• Chemistry: CaSiO3 , Calcium Silicate.
• Class: Silicates
• Subclass: Inosilicates
• Group: Pyroxenoid
• Uses: In ceramics, as a paint filler and as mineral specimens.
• Specimens

Wollastonite is a common mineral in skarns or contact metamorphic rocks. Skarns can sometimes produce some wonderfully rare and exotic minerals with very unusual chemistries. However, wollastonite has no unusual elements in its chemistry and it is somewhat common and not considered very exotic among collectors. Wollastonite forms from the interaction of limestones, that contain calcite, CaCO3, with the silica, SiO2, in hot magmas. This happens when hot magmas intrude into and/or around limestones or from limestones chunks that are broken off into the magma tubes under volcanoes and then blown out of them. It forms by the following formula:

CaCO3 + SiO2 ----> CaSiO3 + CO2

Although not an "exotic" mineral, wollastonite has its uses. It is an important constituent in refractory ceramics (those ceramics that are resistant to heat) such as refractory tile and as a filler for paints. It is easily mined in some places where it is the major component of the metamorphosed rock. Mineral specimens can be interesting with their fibrous habit, pearly luster and some specimens, especially those from Franklin, New Jersey, will fluoresce.

Wollastonite is named for the English chemist and mineralogist W. H. Wollaston (1766 - 1828). Its actual mineralogical name is wollastonite - 1T. The 1T is for the Triclinic symmetry of the most common and first described wollastonite mineral. The reason the 1T is needed is to distinguish it from the much more rare wollastonite - 2M, also known as parawollastonite. Parawollastonite is Monoclinic. These minerals are polymorphs which means that they have the same chemistry, CaSiO3, just different structures (poly means many and morph means shape). There are actually several other rare and obscure polymorphs of CaSiO3 and are given the proposed names of wollastonite - 3T, wollastonite - 4T, wollastonite - 5T and finally wollastonite - 7T. All specimens named just wollastonite are most likely wollastonite - 1T.

PHYSICAL CHARACTERISTICS:

• Color is typically white, colorless or gray.
• Luster is vitreous or dull to pearly on cleavage surfaces.
• Transparency: Crystals are generally translucent and rarely transparent.
• Crystal System is triclinic; bar 1
• Crystal Habits include rare tabular crystals but more commonly massive in lamellar, radiating, compact and fibrous aggregates.
• Cleavage is perfect in two directions at near 90 degrees forming prisms with a rectangular cross-sections. A third direction of cleavage is only good to fair and overall cleavage fragments are elongated splinters.
• Fracture is splintery to uneven.
• Hardness is 5 - 5.5.
• Specific Gravity is approximately 2.8 - 2.9 (average for translucent minerals)
• Streak is white.
• Other Characteristics: Soluble in hydrochloric acid and some specimens will fluoresce.
• Associated Minerals are garnets such as grossular and andradite, vesuvianite, diopside, tremolite, epidote, various plagioclase feldspars and of course calcite.
• Notable Occurrences include Willsboro and other sites in New York, Texas, California and also Franklin, New Jersey, USA; the volcano Monte Somma, Vesuvius, Italy; Perheniemi, Finland; Banat, Rumania; Saxony, Germany; Chiapas, Mexico; Greece; China; Ontario and at the Jeffrey Mine, Asbestos, Quebec, Canada and Tremorgio, Switzerland.
• Best Field Indicators are crystal habit, cleavage, solubility in HCl, fluorescence if present, softness and environment of formation.

 

THE MINERAL WOODHOUSEITE

• Chemistry: CaAl₃PO₄SO₄(OH)₆, Calcium Aluminum Phosphate Sulfate Hydroxide.
• Class: Sulfates; although sometimes classified as a Phosphate.
• Group: Beudantite
• Uses: Only as mineral specimens.
• Specimens

Woodhouseite is a rare mineral that is almost exclusively from a single location at Champion Andalusite Mine on the western slopes of the White Mountain Peak in Mono County, California. It forms flesh-colored to colorless pseudocubic rhombohedrons. The crystals can look nearly cubic, but the angles between the faces are not exactly 90 degrees as is required for a true cube. Wedge-shaped crystals and distorted and modified rhombohedrons are also seen. Faces tend to be curved and striated. It forms in quartz veins with topaz, tourmaline, andalusite and svanbergite, another rare phosphate-sulfate mineral.

Woodhouseite is a difficult mineral to classify in that it has both a phosphate anion group and a sulfate anion group. The phosphate anion group would normally dictate that woodhouseite be classified in the Phosphate Class of minerals. But woodhouseite's sulfate anion is intricate and essential in its structure, while the phosphate anions can be substituted for to at least a limited degree. Some other classification schemes may place woodhouseite in the Phosphate Class however.

PHYSICAL CHARACTERISTICS:

• Color is flesh-colored, pink, pale orange to colorless.
• Luster is vitreous.
• Transparency: Specimens are mostly translucent to small crystals being transparent.
• Crystal System is trigonal.
• Crystal Habits include pseudocubic rhombohedrons and wedge-shaped crystals. Distorted and modified rhombohedrons are also seen. Faces tend to be curved and striated.
• Cleavage is perfect in one direction (basal).
• Hardness is 4.5
• Specific Gravity is approximately 3.0 (average for non-metallic minerals).
• Streak is white.
• Associated Minerals include quartz, topaz, tourmaline, andalusite and svanbergite.
• Notable Occurrence is limited to the Champion Andalusite Mine on the western slopes of the White Mountain Peak in Mono County, California, USA.
• Best Field Indicators are crystal habit, striations, color and locality.

 

THE MINERAL WULFENITE

• Chemistry: PbMoO4, Lead Molybdate
• Class: Sulfates
• Uses: A minor ore of molybdenum and as mineral specimens.
• Specimens

Wulfenite is a nice collection type mineral and is popular as such. Its strong colors, nice luster and one-of-a-kind crystal habits attract the attention of many collectors around the world.

Wulfenite is an enigma in terms of its symmetry. There are conflicting results of various symmetry tests and this usually does not happen. It is either a symmetry of 4 or 4/m. The difference is the disputed existence of a mirror plane perpendicular to the four fold axis. If the mirror exists, then the crystals should have a top that is a mirror image of its bottom. Although most crystals don't show it clearly, the bottom pyramidal faces slant at a different angle from the top pyramidal faces. This demonstrates the symmetry of just 4. However, other tests of its symmetry show a 4/m symmetry. This symmetrical oddity only adds to wulfenite's interest among serious collectors.

PHYSICAL CHARACTERISTICS:

• Color is red, orange, yellow, silver and white.
• Luster is vitreous.
• Transparency: Crystals are transparent to translucent.
• Crystal System is tetragonal; 4/m or 4
• Crystal Habits include very thin square or octahedral pinacoidal plates with pyramidal faces truncating just the edges of the crystal. At times the pyramids become prominant and psuedo-dipyramidal crystal habits are seen, sometimes because of twinning. Prismatic faces are also seen and can make psuedo-cubic crystals. Also encrusting and cavernous aggregates due to intergrowth of crystal plates.
• Cleavage is perfect in one direction.
• Fracture is conchoidal.
• Hardness is 3.
• Specific Gravity is approximately 6.8 (very heavy for translucent minerals)
• Streak is white.
• Associated Minerals are mimetite, limonite, smithsonite, vanadinite and galena.
• Other Characteristics: index of refraction is 2.28-2.40 (very high, but typical of lead minerals).

THE MINERAL WURTZITE

• Chemistry: (Zn, Fe)S, Zinc Iron Sulfide
• Class: Sulfides
• Uses: minor ore of zinc and as mineral specimens
• Specimens

Wurtzite is the not so common cousin of the much more common mineral, sphalerite. Sphalerite and wurtzite are both zinc iron sulfides with the same formula, (Zn, Fe)S. However what makes them different minerals is that they have different structures. The two are called polymorphs (meaning many shapes) and actually share the chemistry with a third, even rarer, mineral called matraite.

Wurtzite's structure is composed of SZn4 tetrahedrons that are stacked in a layered structure with every other layer exactly the same in an AB AB AB ... hexagonal sequence. Sphalerite's structure is an ABC ABC ABC ... sequence of tetrahedrons and results in an isometric arrangement. Matraite has a more complex structure than wurtzite and is trigonal, not hexagonal.

The tetrahedrons in wurtzite all are oriented in one direction and produce the hexagonal (six fold rotational) symmetry. The symmetry is broken in a perpendicular direction to the major axis and results in a hemimorphic crystal structure. In other words, there is no symmetry element, like a mirror or two fold rotational axis, perpendicular to the major axis and thus crystal faces on top of the crystal are not repeated on the bottom of the crystal. Hemimorphic crystals have different looking tops from their bottoms, as if they never completed the opposite, symmetrical, side; therefore the term hemimorphic or half shape. Other minerals that have a hemimorphic character are the tourmalines, hemimorphite (obviously), greenockite and zincite among others.

Crystals of wurtzite are typically six sided pyramids where the hemimorphic character is easily seen as the top of the crystal is the point and the bottom of the crystal is the pyramid's base. Often the crystals are platy with a hexagonal outline and the hemimorphic character is then not easily distinguished. An aggregate of botryoidal crusts with layers of wurtzite, galena and sphalerite is called "Schalenblende" is sometimes cut and polished as an ornamental stone.

PHYSICAL CHARACTERISTICS:

• Color is light to dark brown almost black.
• Luster is resinous to dull.
• Transparency crystals are transparent to translucent.
• Crystal System is hexagonal; 6 m m
• Crystal Habits include tapering hemimorphic six sided pyramids and platy hexagonal crystals. Also seen as acicular radiating crystal groups or as botryoidal crusts layered with galena and sphalerite.
• Cleavage is poor in one direction (basal) and good in three other directions (prismatic).
• Fracture is uneven.
• Hardness is 3.5-4
• Specific Gravity is approximately 4.0 (heavier than average, but light when compared to most metallic minerals).
• Streak is light brown.
• Other Characteristics: Striations on pyramidal faces parallel to base, an index of refraction of 2.36 - 2.38 and some specimens fluoresce orange under UV light.
• Associated Minerals include galena, sphalerite and pyrite.
• Notable Occurrences include Germany; Oruro, Bolivia; Peru; several localities in the USA and England.
• Best Field Indicators are crystal habit, streak, cleavage, softness and associations.