arkose

 
Pronunciation: /ˈɑːkəʊs, -z/

noun

[mass noun] Geology
  • a coarse-grained sandstone which is at least 25 per cent feldspar.

Derivatives

arkosic

Pronunciation: /ˌɑːkəʊsɪk, -zɪk/
adjective

Origin:

mid 19th century: from French, probably from Greek arkhaios 'ancient'