Chiastolite or Cross Stone is a rare variety of Andalusite. Chiastolite name comes from the Greek Chiastos (cross marked). Its black cross inclusion of Graphite and Carbon goes through the entire stone and there are several assumptions on how it was formed, and why it has a cross shape. The first representation of a Chiastolite appears in Laet’s 1648 publication, De Gemmis et Lapidibus. The older books of mineralogy mention Chiastolite under the name lapis crucifer, or lapis cruciatur. Chiastolite specimens were traded in 16 century throughout Europe as a souvenir by pilgrims returning from Santiago de Compostela in Spain. Chiastolite is found in very few places, mainly Spain, Australia, Russia and US. They are Andalusites found along tectonic faults. The origin of the black cross in the stone is not very well known, however it seems to be accepted that impurities probably attach to andalusite crystals as they grow rapidly at their corners, as Frondel suggested in 1934. Being an Andalusite, Cross Stone is a metamorphic rock low in Ca and rich in Al. The Cross Stones are usually brown with golden shades, however they can have white, yellow, pink or red hues. It has a hardness of 6.5- 7.5 on Mohs scale, with an uneven fracture. Andalusite, Sillimanite and Kyanite are three distinct polymorphs of Aluminum Silicate, which are related via pressure and temperature of formation.
Legends According to findings in archeological sites, Native American culture considered Chiastolites sacred, the four veins had a strong significance for them – like four seasons – and they have been extensively used in ceremonies and shaman practices. Shamans often carried pieces of this stone with them in their medicine bags or power bags, and it was a favorite item that they exchanged with others. The black cross of Chiastolite in old Europe was considered a sign of God, and it was revered as a sacred symbol. It was believed to ward off against curses and evil eye.