arkose
A type of sandstone rich in feldspar, typically formed from the weathering of granite. Used in geology.
The arkose in this region contains a lot of feldspar.
砂岩 is a general term for sandstone, while 花崗砂岩 specifically refers to arkose, a feldspar-rich sandstone derived from granite.
花崗岩 is granite, the source rock from which arkose (花崗砂岩) is derived through weathering and sedimentation.
Compound of 花崗 (かこう, 'granite') and 砂岩 (さがん, 'sandstone'), reflecting its composition as a sandstone derived from granitic material.