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RM1270   Japan law quartz twin with cassiterite

Siglo XX mine, Llallagua, Rafael Bustillo, Potosí, Bolivia

The Siglo XX mine is one of the most impressive Bolivian mining localities. It produces some amazing specimens of common species like quartz, few of the with the Japan-Law twin which are are well known in the mineral world. In this sample we can enjoy a good sized Japan-twin quartz crystals, with transparence and luster. This nice twin is disposed on a druse of hyaline quartz crystals.
To give a unique touch to the specimen a group of cassiterite crystals with good brilliance and deep black color, very rich in faces, interpenetrating between them and with some quartz crystals. A superb specimen.

Size: 11.0 x 6.8 x 6.3 cm.
Main crystal: 25 x 15 mm. (macla/twin)


RM129   Sigloite pseudomorph after Paravauxite

Mina Siglo XX, Llallagua, Rafael Bustillo, Potosí, Bolivia

Group of Sigloite crystals pseudomorph after Paravauxite, partially covering the rocky matrix. Paravauxite and sigloite differ chemically by the presence of a single water molecule. Sigloite is white to yellowish. The Siglo XX Mine is the type locality for Sigloite species.

Size: 5.5 x 3.5 x 2.5 cm
Main crystal: 9 x 2 mm

Fluorescent under long wave UV