2007-10-08 20:07:59 · 4 answers · asked by Doodlebug 4 in Science & Mathematics ➔ Earth Sciences & Geology
hardness, quartz is harder than feldspar more so the cleavage the only physical property feldspar has where one can judge whether its quartz or feldspar . Quartz would reflect light therefore shines with more brilliance.
2007-10-08 23:46:17 · answer #1 · answered by Anonymous · 0⤊ 0⤋
And by igneous rock, I presume you mean Granite. Because it would be quite hard to see either mineral in a Rhyolite. Using either the naked eye, or a handlens, you have to look for the clevage, or the striations on the mineral itself. Also, look at the patten in which it is set, if it is octahedral, then it is quartz, which is its mineral habit. Striations may be able to be seen on the Feldspar, but no guarantees. Also you can go by color some what, quartz is clear to milky white, where as Potassium Spar is a pinkish color, and Orthoclase Spar, Plagioclase is just white.
2007-10-09 05:40:59 · answer #2 · answered by Richard F 2 · 0⤊ 0⤋
Feldspar is more opaque, and the surfaces have fine striations. Quartz surfaces are smooth.
2007-10-08 20:32:45 · answer #3 · answered by gp4rts 7 · 0⤊ 0⤋
Quartz is darker, due to its clarity, Feldspar is white or pink
2007-10-08 21:09:33 · answer #4 · answered by jim m 5 · 0⤊ 1⤋