ˈȯ(r)thəˌklās, -āz noun
( -s )
Etymology: German orthoklas, from orth- + -klas -clase
: a mineral KAlSi 3 O 8 consisting of a monoclinic polymorph of common potassium feldspar with sodium often in place of some of the potassium and occurring usually colorless to white, cream-yellow, or flesh-red (hardness 6, specific gravity 2.57) — see feldspar , moonstone