n.
Pronunciation: ' fel(d)- ˌ spär
Function: noun
Etymology: modification of obsolete German Feldspath (now Feldspat ), from German Feld field + obsolete German Spath (now Spat ) spar
Date: 1772
: any of a group of crystalline minerals that consist of aluminum silicates with either potassium, sodium, calcium, or barium and that are an essential constituent of nearly all crystalline rocks