Other inquisitions, 1937-1952

A Strange Way to Categorize Stones and Metals

Consider the eighth category, which deals with stones. Wilkins divides them into the following classifications: ordinary (flint, gravel, slate); intermediate (marble, amber, coral); precious (pearl, opal); transparent (amethyst, sapphire); and insoluble (coal, clay, and arsenic). The ninth category is almost as…

Jan 24, 2012 1

• categorization
• taxonomy