This specimen is highlighted by a crystal of super rare, lustrous, black, schiavinatoite, 1.0 cm across, a niobium, tantalum, borate. The matrix is quartz and rubellite. This crystal is the most LUSTROUS example of the species I have seen, as most are very dull in luster. This is a newly named, extremely rare mineral from Madagascar. I obtained this in exchange from Dr. Pezzotta, who specializes in the minerals of Madagascar and I think could be safely considered the authority on finely crystallized rarities here...he told me these are among the largest fine crystals known for the species. I certainly have seen nothing comparable on the market, and for that matter you don't see much of it at all on the market.