Home > American Minerals – January 11 > MS1991 Sillimanite (Delaware!)

Sillimanite (Delaware!)

Sillimanite is an aluminum silicate, polymorphous with kyanite and andalusite. Sillimanite serves as an indicator of both high-temperature and high-pressure metamorphic conditions. The mineral name honors Benjamin Silliman (1779-1864), professor of chemistry at Yale University and founder of the American Journal of Science. Bowen (1824) originally described the species from Connecticut.

This specimen is a foliated rock consisting mainly of silky fibrous sillimanite, with minor quartz and mica. A record of this occurrence appears in the 1892 edition of Dana's System of Mineralogy. Sillimanite became the state mineral of Delaware in 1977.

Price: $75

Item code: MS1991

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