Materials & Techniques
Anthracite is a variety of coal that has a high luster. It has the fewest impurities and is the least plentiful form of coal. Anthracite is similar in appearance to jet and is sometimes used as an imitation of a mineraloid. Geologically, the largest anthracite deposits in the world are found in northeastern Pennsylvania, in Crested Butte, Colorado, in British Columbia, Canada, in the Crow's Nest part of the Rocky Mountains in Canada, and in various places throughout the Andes in Peru.
Getty Vocabulary, AAT (anthracite (coal): AAT: 300015140)
"Anthracite," Wikipedia, accessed May 26, 2015, http://en.wikipedia.org/wiki/Anthracite.