orthoclase

noun or·tho·clase \ˈȯr-thə-ˌklās, -ˌklāz\

Definition of ORTHOCLASE

: a monoclinic mineral of the feldspar group consisting of a silicate of potassium and aluminum

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German Orthoklas, from orth- + Greek klasis breaking, from klan to break — more at clast

First Known Use: 1849

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