CHROMIUM AND VANADIUM MINERAL ECOLOGY

Minerals containing chromium (Cr) and vanadium (V) as an essential element display systematic trends in their diversity and distribution. For Cr minerals, we employ data for 85 approved terrestrial species (rruff.info/ima, as of 15 April 2016), representing 4248 mineral species-locality pairs (mindat.org and other sources, as of 15 April 2016). We find that Cr-containing mineral species, for which 30% are known at only one locality and more than half are known from 3 or fewer localities, conform to a Large Number of Rare Events (LNRE) distribution. Our model predicts that at least 114 ± 12 (1σ) Cr minerals exist in Earth’s crust today, indicating that at least 29 species have yet to be discovered. We also performed similar analysis on 228 V mineral representing 5589 mineral species-locality pairs. We find that V-containing mineral species, for which 28% are known at only one locality and more than half are known from 3 or fewer localities, also conform to the LNRE distribution. Our model predicts that at least 314 V minerals exist in Earth’s crust today, indicating that at least 86 species have yet to be discovered.