Abundances, distributions and patterns of discovery of new minerals

Mineral species are known to be heterogeneously distributed throughout the Earth such that a relatively small number of minerals make up a large proportion of the lithosphere while the majority of all known minerals are rare and have been identified at only a small number of locations that frequently exhibit high levels of species richness. Intuitive understandings of mineral scarcity and abundance are reconsidered through the characterisation of the quantitative aspects of spatio-temporal trends in new mineral discovery. Using data drawn from online mineralogical databases, it is found that the Earth's mineral hotspots exhibit an exponential distribution of species abundance, while those same mineral hotspots exhibit a power-law distribution in the number of minerals first recognised at those locations. That is, locations rich in first occurrences are extremely rare, even when considering only the Earth's most species-rich mineral locations. Global distributions of mineral scarcity and abundance can be estimated from the number of mineral-location pairs for each species reported in a database. Two-thirds of all known species have been reported from ten or fewer locations and the frequency distribution of these mineral-location pairs exhibit a power-law distribution that extends with increasing dispersion over several orders of magnitude of mineral abundance. Initially, nearly all minerals are first reported from only their type locality. Over time, additional occurrences of newly discovered minerals are reported at an average rate of one new location per mineral every 5.5 years. As a result, the percentage of minerals that were discovered in a given year that continue to be known only from their type locality is found to decline exponentially over time. However, a few minerals remain known from only their type locality for long periods, including some that were first identified in the 19 th Century. Conversely, other recently identified minerals have been subsequently recognised at locations spanning a wide geographic range such that the number of minerals with cosmopolitan distributions is found to increase exponentially over time. Taken together, these several quantitative representations of mineral distributions lend structure and refinement to qualitative and intuitive notions of the scarcity and abundance of Earth's many minerals.