Chiastolite

Chiastolite specimens were distributed throughout Europe from the 16th century, as an amulet or souvenir provided by the pilgrims returning from Santiago de Compostela (Saint James of Compostella), in Spain.

The first figure of a chiastolite appears in Laet's book De Gemmis et Lapidibus, published in 1648.

[3] In areas around Georgetown, California, US, metamorphosed sediments contained andalusite and chiastolite in a graphite-rich metasediment.

Mineralogically the occurrence is important because all three white mica phases are present in an equilibrium assemblage.

This concentrated impurity deposit forms a re-entrant as it is absorbed by the growth of the andalusite porphyroblast.