Learn how to say Orthoclase correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word orthoclase:
a common rock-forming mineral occurring typically as white or pink crystals. It is a potassium-rich alkali feldspar and is used in ceramics and glass-making.
mid 19th century: from ortho- ‘straight’ + Greek klasis ‘breaking’ (because of the characteristic two cleavages at right angles)