• Webster's Revised Unabridged Dictionary
    • n Felsite (Min) A finegrained rock, flintlike in fracture, consisting essentially of orthoclase feldspar with occasional grains of quartz.
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Century Dictionary and Cyclopedia
    • n felsite A compact, very hard rock, almost flinty in texture. made up of quartz and orthoclase feldspar intimately mixed. It is a rock of eruptive origin, occurring in large masses in the older part of the geological series, from the Silurian up to the Jurassic, in the form of bosses and dikes, or in regular volcanic overflows. Also called felstone and petrosilex.
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Chambers's Twentieth Century Dictionary
    • n Felsite fel′sīt a fine-grained, compact rock, a variety of quartz-porphyry—also Fel′stone
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Webster's Revised Unabridged Dictionary
Cf. Feldspar
Chambers's Twentieth Century Dictionary
Fr.,—Ger. fels, rock.


In literature:

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"