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PHOE9-1 Phoenicochroite $32
Potter-Cramer Mine, Vulture District
Vulture Mts, Maricopa Co., Arizona
4.8 cm x 4.2 cm x 3.9 cm
A miniature-sized sample with a coating of resinous, red Phoenicochroite, Pb2[O|CrO4]. It requires 60 x on my microscope to discern any crystals, and there are only a few of them hiding out on this specimen.
click on images
for larger view - image on right is 7 x 7mm
BOTRY9-1 Botryogen, Pickeringite & Copiapite $48
Libiola
Mine, Sestri Levante, Genova Province, Liguria, Italy
2 cm x 3 cm x 2 cm; largest crystal size ~ 1.5 mm
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for larger view
BOBI9-1 Bobierrite $35
Iron Mine, Kovdor Massif, Kola Peninsula
Murmanskaja Oblast', Northern Region, Russia
2.6 cm x 3.6 cm x 2.5 cm; largest crystal = 1.1 cm
Bobierrite (Mg3(PO4)2·8H2O) is another mineral that forms in guano or fossil deposits. The shiny gray fan of flat-lying crystals in the center of the photo seems too pretty to be associated with guano or fossils, however!
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for larger view
BIRN9-1 Birnessite on Calcite $22 SOLD
300'
level, Gold Hill
Mine, Clifton District
Deep Creek Mts, Tooele Co., Utah
5 cm x 4 cm x 4.2 cm
Birnessite, ((Na,Ca)0.5(Mn4+,Mn3+)2O4· 1.5H2O), here seen coating an otherwise pretty little Calcite (CaCO3) stalactite, is certainly one of the ugliest of ugly minerals. Yet it plays some important roles in nature: it is present in bacterially-precipitated manganese oxides, marine manganese nodules and the "desert varnish" that forms over rain-starved soils. It is also a frequent pseudomorphing agent. On this specimen, it coats the Calcite and adds a few arborescent crystal forms of its own.
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for larger view
MH9-1 Barnesite (TL), Hewettite and Metahewettite (TL) $48
Cactus
Rat Mine, Cisco, Yellow Cat District
(W. part of Thompsons District), Grand Co., Utah
9.5 cm x 4.5 cm x 2.7 cm
I believe that the Barnesite (Na2[V2O6|V4O10] · 3H2O) crystals are the brightest red ones, as in the center of the right-hand photo; the Metahewettite (Ca[V2O6|V4O10] · 3H2O) crystals are the lighter copper-colored ones, and the Hewettite (Ca[V2O6|V4O10] · 9H2O) are the chocolate brown crystals. But these species are very similar, and I'm just going off the descriptions in mindat.org. Certainly there's enough going on in this specimen to provide hours of exploration if you have a loupe or a microscope to reveal the details.
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on image for larger view
VAL6-1 Valleriite $75
Whitehorse
Copper Belt, Whitehorse Mining District
Yukon Territory, Canada ex. Joe Cilen #6292
3.2 cm x 2.6 cm x 2.6 cm
Patches of bronze-colored Valleriite (Fe2+,Cu)4(Mg,Al)3[(OH,O)6|S4], a rare sulfosalt, richly infuse this specimen. Since Joe Cilen had a collection numbering in the tens of thousands, I guess this one (#6292) was an early acquisition. The specimen comes with his label.
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for larger view
BOUR9-1 Bournonite $75
Pulacayo
Mine, Huanchaca, Quijarro Province,
Potosí Department, Bolivia
3.1 cm x 2.8 cm x 0.8 cm
Bournonite, PbCuSbS3 is a relatively rare copper sulfosalt, best known for forming distinctive "cogwheels" as evidenced in the two photos above. The cogwheels are due to contact twinning or polysynthetic twinning. This specimen has some very fine cogwheels.
click on image
for larger view
BOUR9-2 Bournonite $48
Mure
Mine, Isère, Rhône-Alpes, France
1.6 cm x 2.1 cm x 1 cm
Bournonite, PbCuSbS3 is a relatively rare copper sulfosalt, best known for forming distinctive "cogwheels" as evidenced in the two photos above. The cogwheels are due to contact twinning or polysynthetic twinning. The cogwheels on this specimen are not as distinct as in the previous specimen from Bolivia, but the luster is much brighter.
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