Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "feldspath" in a sentence
"Our path, on setting out, lay along a narrow passage between rocks of granite, quartz, and feldspath; the direction north."
"Near the opening of the mountain, where the water is found, at some distance below the highest summit, I found the rock to be porphyry of a light reddish colour, close grained, with small veins of feldspath, much resembling the porphyry I saw last year, in Wady Lamoule, beyond the Second"
"I saw only a few specimens of green porphyry, with red slabs of feldspath; the greatest part being red porphyry, and porphyry schist."