Antiperthite

This attractive specimen features a well-formed antiperthite crystal from the Wade Property, East Pitcairn, St. Lawrence County, New York. The principal crystal displays creamy-white colour with a soft pearly lustre and good crystal form, perched on a feldspathic matrix. Close inspection reveals the subtle exsolution textures characteristic of antiperthite, making it an excellent representative example of this unusual feldspar variety.

The Wade Property lies within the famed Grenville Province, one of the world's classic regions for complex metamorphic mineralogy and unusual feldspar occurrences. Antiperthite is an intergrowth of two feldspars formed through slow cooling and exsolution, in which potassium feldspar occurs as lamellae within a plagioclase host—the reverse of the more familiar perthite. Well-crystallized specimens are uncommon and are sought after by collectors interested in feldspars, petrology, and classic Grenville localities.

A handsome and increasingly difficult-to-find specimen from one of the best-known antiperthite localities in North America.