felsitic

“A gigantic clummmp of felsitic debris, last year, off the coast of Denmark, she criticized its, "just about to fall into one of those mirthless laughs we edge away from," its crystalline structure, for twenty minutes.”

Gravity's Rainbow

“A patch of granitic and felsitic rocks form Parys Mountain, where copper and iron ochre have been worked.”

Encyclopaedia Britannica, 11th Edition, Volume 2, Part 1, Slice 1

“The latter are represented by large contemporaneous deposits of tuff and felsitic lava which in the Snowdon District are several thousand feet thick.”

Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy"

“As its name implies, it contains many caves in the felsitic conglomerate overlying the region.”

Unknown Mexico, Volume 1 (of 2) A Record of Five Years' Exploration Among the Tribes of the Western Sierra Madre; In the Tierra Caliente of Tepic and Jalisco; and Among the Tarascos of Michoacan

“Set in and on the black flanks, and looking from afar like the gouts of a bloodstone, are horizontal beds, perpendicular spines, and detached blocks of felsitic porphyry and of rusty-red syenite, altered, broken, and burnt by plutonic heat.”

The Land of Midian — Volume 1

“Mr. Keita reports that gold has been found in several sets of quartz veins in and around felsitic dykes within some of the areas of orpaillage.”

TradingMarkets

“a bloodstone, are horizontal beds, perpendicular spines, and detached blocks of felsitic porphyry and of rusty-red syenite, altered, broken, and burnt by plutonic heat.”

The Land of Midian