It exists in a felsite dyke immediately on the coast.
"Getting Gold" by J. C. F. Johnson
The lode is a large irregular one of pure arsenical pyrites, existing in a felsite dike near the sea coast.
"Scientific American Supplement, No. 841, February 13, 1892" by Various
The rough felsite blocks of which they were composed were surprisingly large, considering the diminutive size of the cabins.
"Unknown Mexico, Volume 1 (of 2)" by Carl Lumholtz
Felsitic lavas and tuffs occur in the Middle Devonian of Australia.
"Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 3" by Various
The felsite sheets are well represented in Holy Island.
"Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 6" by Various
Felsitic rocks are sometimes silicified and have their matrix replaced by granular aggregates of cloudy quartz.
"Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 2" by Various
Felspar in Colorado and felsite magnesian slate in Newfoundland carry gold.
"The Romance of Industry and Invention"