adularia
noun
ad·u·lar·ia ˌa-jə-ˈler-ē-ə 
ˌa-dyə-
: a transparent or translucent orthoclase
Word History
Etymology
borrowed from Italian, from Adula, mountain group in the Lepontine Alps east of St. Gotthard Pass (Switzerland) + -aria (borrowed from Latin -āria, feminine singular of -ārius -ary entry 1)
First Known Use
1789, in the meaning defined above