Displaying 1 - 50 of 288
Catalog # Name Description
1 Gypsum Small seam of clear crystals.
2 Barite Calcite vein-stuff in carboniferous shale.
3 Gypsum Translucent, blocky crystal group.
4 Barite Pinkish blades on dark calcite matrix with clear calcites.
5 Heubnerite Crystals in quartz.
6 Melanterite Melanterite is one of only a few water soluble sulfate minerals. It forms in the near-surface secondary oxidation zone of ore deposits usually late in their development. In many mines, melanterite is an ongoing precipitate or efflorescent forming white to green encrustations, crystal aggregates and stalactites right on the sides of the mine's shafts. The primary source of the iron for melanterite is iron sulfides such as pyrite, pyrrhotite, marcasite and chalcopyrite. A technique for removing copper from the copper sulfate mineral chalcanthite is responsible for the naming of an alternate name for melanterite. Chalcanthite, like melanterite, is soluble in water and it thus makes a solution of copper sulfate. If metallic iron is added to the solution, then metallic copper precipitates, leaving a solution of iron sulfate. This left-over solution has the same composition as a solution made from dissolving melanterite. The alternate name for melanterite is "copperas", from the Greek meaning "copper water", an allusion to the left-over solution. In a way, this could be thought of as "copper-providing water". Attractive crystals of melanterite with a beautiful blue-green color are know to exist and are sought after. The shades toward blue come from impurities of copper which can substitute for as much as one third of the iron. The more copper, the bluer the crystals. Generally melanterite is known as having a white or green color. Melanterite is also the name of a group of only five monoclinic sulfates of which melanterite is the only somewhat common member. Members of this group have the same basic structure as melanterite, but can have in place of iron, ions of manganese, zinc, cobalt and copper. These are the members of the Melanterite Group: Bieberite (Hydrated Cobalt Sulfate), Boothite (Hydrated Copper Sulfate), Mallardite (Hydrated Manganese Sulfate), Melanterite (Hydrated Iron Sulfate), Zinc-melanterite (Hydrated Zinc Copper Iron Sulfate) PHYSICAL CHARACTERISTICS: Color is white, green, yellowish green or blue-green. Luster is vitreous to silky. Transparency: Crystals are translucent to slightly transparent. Crystal Habits include stubby prismatic or blocky to tabular crystals, sometimes as pseudo-octahedrons. Also acicular, fibrous and capillary and found as encrusting, stalactitic and concretionary masses. Cleavage is perfect in one direct but only distinct in another. Fracture is conchoidal. Hardness is 2 Specific Gravity is approximately 1.9 (well below average). Streak is white. Other Characteristics: Is soluble in water and may deteriorate with absorption of water. The taste has a sweet, astringent and metallic character. Associated Minerals are epsomite, chalcanthite, gypsum, pyrite, pyrrhotite, marcasite and chalcopyrite. Notable Occurrences include Minas de Rio Tinto, Spain; Rammelsberg, Harz Mountains, Germany and Falun, Sweden; and in the United States at Ducktown, Tennessee; South Dakota; Colorado; Bigham Canyon, Utah; Comstock Lode, Lincoln County, Nevada; Butte, Montana; at several mines in Arizona and at The Geysers in Sonoma County and at Leona Heights, Alameda County, California. Best Field Indicators are crystal habit, low density, associations, solubility in water, taste and color.
7 Wolframite None
8 Barite Barite/sandstone rose.
9 Gypsum Concretion.
10 Barite Misidentified as dolomitic material.
11 Barite Misidentified as dolomitic material.
12 Wulfenite None
13 Scheelite Pale gray, massive.
14 Wulfenite Small, golden cubes in vugs.
15 Barite Massive, pink.
16 Gypsum Curved crystal groups on matrix, selenite.
17 Scheelite Massive, grey.
18 Wolframite (Ferberite) Black, some crystal faces showing.
19 Wolframite (Ferberite) With Tunctate decomposition.
20 Wolframite (Ferberite) Small, sparkly crystals on matrix.
21 Wolframite (Ferberite) Blades of Ferberite in quartz.
22 Wolframite Massive pyrite with copper crystals.
23 Gypsum Variety alabaster, cut & polished semi-circle.
24 Tungstite On Ferberite. With Ward's label. Color: GR, WH
25 Celestite Blue, fibrous.
26 Celestite Clear blue-gray chunks.
27 Celestite Pale gray. Possibly not celestite.
28 Barite One specimen - tan calcite crystals.
29 Barite Massive, white.
30 Barite White, lamellar.
31 Barite Crystalline massive.
32 Barite White interlocked crystals.
33 Barite White, lamellar, massive.
34 Barite Massive, white (heavy spar).
35 Barite White barite crystals with malachite.
36 Barite Clear, gray tabular crystals.e matrix with clear calcites.
37 Gypsum Impure; with curved crystals of selinite. In exhibit from 1992-2006
38 Gypsum Dark gray, mssive, showing cleavage faces.
39 Gypsum White, massive, showing cleavage planes.
40 Gypsum White, massive; initials E. R. scratched on surface
41 Gypsum Var. alabaster; white, massive.
42 Gypsum Gypsum w/clay; gray, some clear crystals to 3/4"
43 Gypsum Satin spar.
44 Gypsum Fibrous, white to orangish.
45 Gypsum Small brown crystals encrusted with rock salt.
46 Gypsum Ver. selenite; 2 crystals.
47 Gypsum Gypsum crystal in clay.
48 Gypsum Gray crystals.
49 Gypsum None
50 Gypsum White, massive, pieces of a 3/4" slab, unpolished var. alabaster