130-A23-2

Displaying 1 - 49 of 49
Catalog # Name Description
1 00.2.11.283.0006 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.
2 00.2.5.137.0002 Tungstite On Ferberite. With Ward's label. Color: GR, WH
3 1970.74.1004M Hanksite Gray, botriodal.
4 1970.74.1091M Gypsum var. Selenite Selenite crystal.
5 1970.74.1092M Gypsum var. Selenite Clear crystal.
6 1970.74.1214M Linarite Blue coating on quartz.
7 1970.74.1254M Gypsum var. Selenite Var. selenite; clear tannish cleavage fragments.
8 1970.74.1333M Gypsum var. Selenite Gray translucent crystals.
9 1970.74.1334M Gypsum var. Selenite Clear, gray crystals - selenite.
10 1970.74.1413M Gypsum var. Selenite Bum nodule.
11 1970.74.1653M Gypsum var. Selenite None
12 1987.3.0024 Gypsum Transparent, tan plate.
13 1990.53.0072 Gypsum Var. selenite, single crystals & large cluster w/sand inclusions; clear & brown
14 1990.53.0073 Gypsum Var. selenite, gray crystal group.
15 1990.53.0074 Gypsum Massive, iron stained white with cleavage faces
16 1990.53.0075 Gypsum Var. selenite, clear gray crystals w/swallowtail formation
17 1990.53.0076 Gypsum Curved cream crystals.
18 1990.53.0077 Gypsum Var. selenite; crystals heavily sand-included brown & clear
19 1990.53.0078 Gypsum Selenite crystal cluster; clear.
20 1990.53.0079 Gypsum Var. selenite, flat, tan sand included crystals; a. and b.
21 1990.53.0080 Gypsum Var. selenite, "hourglass" crystals; singles & clusters.
22 1990.53.0080a Gypsum Var. selenite, cluster of fine sand-included crystals
23 1990.53.0082 Gypsum None
24 1990.53.0083 Gypsum Flat cluster of thick gray transparent crystals.
25 1990.53.0216 Gypsum Var. selenite, tan attached "roses".
26 1990.53.0217 Gypsum Var. selenite, tan "rose".
27 1990.53.0218 Gypsum Var. selenite, single & crystal groups.
28 1990.53.0219 Gypsum Var. selenite, reddish brown "rose".
29 1990.53.0220 Gypsum Flat, orange selenite with inclusions.
30 1990.53.0221 Gypsum Var. selenite, 14 1/2" connected "roses"; Note: Specimens not numbered - not suitable space.
31 1990.53.0222 Gypsum Reddish brown selenite "rose".
32 1990.53.0223 Gypsum Var. selenite. clusters of connected "roses"; Note: specimens not numbered - no suitable surface.
33 1990.53.0224 Gypsum Var. selenite. cluster of white crystals.
34 1990.53.0225 Gypsum Var. selenite; clear, clean ball of crystals.
35 1990.53.0226 Gypsum Var. selenite; cluster of sand encrusted & included crystals
36 1990.53.0227 Gypsum Miniature - cluster of sandy brown crystals; TN - singles.
37 1990.53.0228 Gypsum Clear, clean crystal ball.
38 1990.53.0229 Gypsum None
39 1990.53.0232 Gypsum Var. selenite roseick gray transparent crystals.
40 1990.53.0236 Gypsum None
41 1990.53.0242 Gypsum Var. selenite; specimen d - single clear crystal; specimens abcd - dlusters of small crystals with 2 or 3 larger protruding crystals
42 1990.53.0282 Gypsum Var. satin spar; white, striated.
43 1990.53.0365 Gypsum Transparent, golden, massive with smaller clear crystals attached
44 1990.53.0366 Gypsum Clear crystals - large, blocky.
45 1994.11.0006 Gypsum Variation, selenite; typical. Color: CL
46 1994.11.0007 Gypsum Var. selnite; typical large crystal. Color: CL,GY
47 1995.36.0027 Gypsum Var. selenite, with curved crystals. Color: WH Gypsum image
48 1996.16.0018 Gypsum Variety selenite. Color: WH,BR 1996.16.0018 (Gypsum) image
49 2006.15.0007 Gypsum (Selenite rose variety) 340 gram uniformly gray colored specimen of gypsum. This particular type is known as selenite rose because of the petal like structure of the large crystals it contains. Color: GY