Fluorite from Mont St-Hilaire
Ferberite $48 SOLD
A hefty crystal of solid Ferberite FeWO4 that is terminated on top, front and sides, contacted on the bottom, and coated with small disc-shaped Calcites on the back.
FERR9-1 Ferrierite-Mg $28 SOLD
Monastir, Cagliari Province, Sardinia, Italy
4 cm x 5 cm x 3 cm; diameter of ball = 6 mm
Ferrierite-Mg (Mg,Na2,K2,Ca)3-5Mg[Al5-7Si27.5-31O72]·18H2O is another rather rare zeolite. A few colorless Heulandites are nestled up against the Ferrierite balls, and a particularly nice cluster is located in front of the central Ferrierite ball on the photo on the left, which partially blocks the Ferrierite from the camera's view.
Fluorite on Amethyst in Geode $650
Mahodari, Nasik District, Maharashtra, India
A very large, complete geode containing yellow botryoidal Fluorite (CaF2) on deepest purple Amethyst (Quartz : SiO2), with green exterior patches of Celadonite (K(Mg,Fe2+)(Fe3+,Al)Si4O10(OH)2). The second photo shows how well the 2 pieces fit. This nodule was in my geode-nodule case when it received first place 4 times at the San Diego County Fair. Research by P. Vasconcelos has shown that the Amethyst geodes in Brazil (similar to the geodes in India like this one) are younger than the volcanic basalts in which they formed, thereby supporting the theory that the spaces in the basalts formed first and were filled at a later date by hydrothermal action.
FL5-71 Fluorite $195 SOLD
Mine, Xianghualing Sn-polymetallic ore field
9.5 cm x 8.2 cm x 4.1 cm; crystals 4 cm on edge
This Fluorite (CaF2) specimen just would not commit to being photographed by an amateur, so use the top two photos as an indication of the color, which is a very even, light green throughout, with NO dark or light spots. The bottom two photos give a better indication of the shape - cubes to 4 cm on edge with beveled edges. The cube faces are smooth with a few visible growth hillocks; the bevels separating faces appear rough because they have hundreds of tiny growth planes. The two largest cubes have interesting double bevels. The back side is a contact surface where the piece grew on matrix. The right edge of the specimen where it looks like the crystal is indented is a natural, stepped area where the growth stopped short of the face plane. A glowing, geometric, transparent work of natural art and physics.
Circle Cement Quarry, Eastgate, Weardale
7 x 5.5 x 4 cm
The Weardale Fluorites (CaF2) are famous for their eye-popping blue fluorescence under LWUV. The fluorescence is so strong that it even contributes to a color change when the mineral is taken outside to be illuminated by the sun (and hence gets a dose of the sun's UV). They respond almost as well under SWUV.
FB6-1 Fluorite on Barite $125 SOLD
Emilio Mine, El Fito, Loroñe, Villaviciosa, Asturias, Spain
12 cm x 9 cm x 6 cm
A heavy matrix is covered with white blades of Barite (BaSO4) topped with colorless Fluorites (CaF2) in the form of cubes and rectangular solids. A sprinkling of tiny Calcites (CaCO3) looks like a sugar coating, and tiny dark sulfides (probably Marcasite, FeS2 or maybe Pyrite, also FeS2) provide a contrasting accent, especially nice when they streak the edge of a Barite blade. The piece comes with a collection card saying the previous owner paid 140 euros for this specimen in 2003.
FL5-09 Fluorite with Natural Etching $95 SOLD
Mine, Goose Creek Mine Group
11 cm x 9 cm x 4 cm
On the front side, natural etching has turned these Fluorites (CaF2) into thin, tabular crystals by preferentially removing material parallel to the crystal faces. This highlights the dark phantom center that some of them have. On the back side, the etching has proceeded in the more usual fashion, working the Fluorite into finely grained and textured surfaces. The whitish material on the front side fluoresces yellow under SWUV, so it probably has petroleum in it, as does portions of the Fluorite.
on Muscovite $68 SOLD
Clear, colorless Fluorite on silvery Muscovite. The large complex Fluorite crystal approximates an octahedron with lightly frosted faces alternating with clear ones. The clear faces host dozens of smaller clear faces sprouting like mathematical fractals. The frosted faces have only very tiny secondary faces. Quite a challenge to the crystallographer!
FKH10-1 Fluoro-potassichastingsite (TL) $28 SOLD
Greenwood Mine, Woodbury Township, Orange Co., New York
4.5 cm x 3.1 cm x 2.3 cm
Lovers of black rocks, rejoice! At Tucson there appeared a relatively new species (confirmed in 2005) of amphibole, fresh from the type (and ONLY) locality. The specimen is a solid mass of crystal faces, supposedly with some Magnetite ore present also, but all I can see is Fluoro-potassichastingsite [K][Ca2][Fe2+4Fe3+][(F,OH)2|Al2Si6O22].
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