A specimen of dallasite from Vancouver Island

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]

References

  1. ^ [1]Nixon, G.T., Larocque, J., Pals, A., Styan, J., Greene, A.R., and Scoates, J.S. (2008), High-Mg Lavas in the Karmutsen Flood Basalts, Northern Vancouver Island (NTS 092L): Stratigraphic Setting and Metallogenic Significance((citation)): CS1 maint: multiple names: authors list (link)
  2. ^ Hudson Rick (1999), A Field Guide to Gold, Gemstone and Mineral Sites of British Columbia. Volume 2. Orca Book Publishers.
  3. ^ VanLandingham, Sam L. (1985), Geology of world gem deposits
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