Vote for your favorite mineral in #MinCup26! - Sphalerite vs. Anorthite Both zinc ore Sphalerite and calcium plagioclase feldspar Anorthite have perfect cleavage that will split cleanly if you hit them with a hammer, but only one can claim a larger split of your votes!
A metallic crystal of 4.23 mm, purchased at Lorano, was studied by Giovanni D'Achiardi in 1911. On the basis of the crystallographic data and physical properties, D'Achiardi was not able to identify this mineral. In his opinion, the mineral could be a new species and the only known mineral similar to it was galena (D'Achiardi, 1911 a). Some months later, D'Achiardi published the results of the qualitative chemical analysis, showing that the unknown mineral contains Cu and S, but not Pb, As, Sb, or Bi (D'Achiardi, 1911 b). Consequently, it could not be galena and it did not correspond to any Cu sulfide owing to its crystal habit and the other physical properties. This specimen remained unclassified and was kept in the mineralogical collection of the Pisa University until the 1970s, when Paolo Orlandi found it, accompained by the label "New copper mineral?". Through X-ray diffraction, Orlandi (1974 b) was able to determine the unit-cell parameter; furthermore, he collected new chemical data, indicating the presence of Cu, V, and S. The unknown copper sulfide of Giovanni D'Achiardi was actually sulvanite.
Lorano quarries, Torano quarrying basin, Carrara, Massa-Carrara Province, Tuscany, Italy