Dallasite

This article is about a type of rock found in British Columbia. For the definition of someone from Dallas, Texas, see Dallas, Texas.

Dallasite is a breccia made of subequant to rectangular or distinctly elongate, curvilinear shards that represent the spalled rims of pillow basalt (see: Hyaloclastite). This material is commonly partly altered to chlorite, epidote, quartz and carbonate, for which the local term 'dallasite' has been coined.^[1] The stone dallasite is named after Dallas Road, Victoria, British Columbia. It is considered the unofficial stone of British Columbia's capital city.^[2] Dallasite is found in Triassic volcanic rocks of Vancouver Island and is considered the third most important gem material in British Columbia.^[3]

A specimen of dallasite from Vancouver Island