[Cu.sub.2]ZnSn[S.sub.4] is the quaternary compound semiconductor of stannite structure, and its main ingredient is the mixture of [Cu.sub.2]FeSn[S.sub.4] and [Cu.sub.2]ZnSn[S.sub.4].

Ito, "Sprayed films of stannite [Cu.sub.2]ZnSn[S.sub.4]," Applied Surface Science, vol.

Nakazawa, "Electrical and optical properties of stannite type quaternary semiconductor thin films," Japanese Journal of Applied Physics, vol.

X-ray diffraction analysis indicates that the replacing substance is a mixture of chalcopyrite, pyrite and a mineral close to stannite.

Mathias had set out a few "new" finds, and was especially proud of a specimen of andorite with associated zinkenite and stannite from the San Jose mine, Oruro, Bolivia.

Actually (according to Alfredo Petrov), the San Jose and Itos "mines" are shaft workings which exploit the same rich silver orebody from opposite sides; thus these two well-known localities for world-class specimens of andorite, stannite, zinckenite and other sulfides and sulfosalts may perhaps overlap ambiguously in some places.

Flat, striated, compound andorite blades to 9 cm, metallic gray and medium-lustrous, are decorated with nests of small, brilliant black, iridescent needle crystals of zinkenite; other associated species, in microcrystals, include stannite and pyrite.

Fine specimens containing sharply formed stannite and bornite crystals occur locally.

In 2001 and 2002 a few black crystals measuring about 1 cm and showing a greenish coating were recovered and were thought to be the species "pandaite," but soon it turned out that these in fact are extraordinarily large crystals of kesterite, a copper and zinc sulfide related to stannite. The best discovery took place early in 2003, when a number of very well-developed crystals, probably the finest known for the species, were found in a cleft.

Some of the minerals, including ferberite, arsenopyrite, stannite and fluorite, are found in quartz veins, while others, including scheelite, chalcopyrite and bismuthinite, are found in the skarn.

[Contribution to the Knowledge of Bolivian Mineralogy - III, Stannite.]

Associated minerals are: (dominant) miargyrite; (less frequent) pyrargyrite, stannite and kesterite; (trace) andorite, diaphorite, robinsonite, galena, chalcopyrite, sphalerite and pyrite.

Phenomenal specimens of Llallagua purple fluorapatite, wavellite, stannite and the rarer tin sulfosalts, pyrrhotite.

Associated minerals are: quartz, pyrite, pyrrhotite, sphalerite, chalcopyrite and stannite.