Gaidonnayite, Genthelvite, Gmelinite, Gonnardite,
Genthelvite in Microcline $37.50 SOLD
A piece with fine-grained, green-blue Amazonite chunks from the pegmatite at Bakstevalåsen, Norway. It contains dark red crystal sections measuring up to 3 mm of Genthelvite (Zn4Be3[S|(SiO4)3]). This Genthelvite is rich in manganese and iron which gives it the red color, unlike the brownish specimens from Mont Saint-Hilaire. The Amazonite fluoresces white under SWUV. Another example to illustrate that rare minerals are not always ugly and black!
GILL9-1 Gillespite and Sanbornite $18 SOLD
Madrelena Mine, Tres Pozos, Baja California Norte, Mexico
3.5 cm x 2.3 cm x 2.5 cm
Bright red Gillespite (BaFe2+[Si4O10]) in a matrix with colorless Sanbornite (Ba2[Si4O10]). The Sanbornite fluoresces cream in LWUV and SWUV.
Görgeyite $150 SOLD
A large, nearly complete crystal of the extremely rare sulfate Görgeyite (K2Ca5(SO4)6•H2O) with an old Russian-style number tag on the bottom. The faces are smooth and have the silky feel of a Calcite. The left termination face in the left-hand photo is especially complex, looking like waves on a beach. The bottom edge of the crystal is contacted and there is a chip on the upper left edge (visible in right-hand photo), but it is still an exceptionally large and good crystal for such a rare species. It fluoresces yellow-orange under SWUV.
Seco Mine, Itinga, Jequitinhonha valley,
found a few of these
enigmatic Brazilian specimens at Tucson labeled as Guimarãesite/Greifensteinite/Zanazziite
since they are either combinations of the three beryllium phosphates,
or so indistinguishable that whichever is present might as well represent
all three, as you can see from comparing their chemical formulas:
do Piauí claim, Piauí valley, Taquaral, Itinga,
From a slightly different location still within the type locality (TL) designation of Taquaral, here is another of the triple beryllium phosphates Guimarãesite/Greifensteinite/Zanazziite. This time the matrix is bladed Albite, still accompanied by prismatic Eosphorite and the unknown cream-colored mineral, with 8 large beryllium phosphate balls.
PGH9-1 Phosphorescent Gypsum $32 SOLD
3.4 x 1.7 x 1.2 cm
The cool thing about this neat little Gypsum crystal is that when it fluoresces, you see an hourglass shape! These used to be very common, but now they seem to be getting hard to find.
Gypsum (variety Selenite) pseudomorph of Halite $20SOLD
A distorted, hoppered cube of gray Gypsum (Ca[SO4] · 2H2O) variety Selenite, assuming the form of a large, intricate Halite (NaCl) crystal. Dale Harwood, the collector of this specimen, says that Vandenberg Air Force Base has now closed the road that gives access to this site; so unless they restore access, no more will be coming out.
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