natural mixture of aluminium silicates, alkalines and alkaline-earth and aluminium hydrosilicates, natrolite (43-46,5 %) and feldspar, natrolite - a zeolite mineral: (...). It sometimes contains appreciable calcium, and usually occurs in slender, acicular or prismatic crystals., a group of fine grained extrusive rocks primarily composed of alkali feldspar (esp. anorthoclase or sanidine) and with nepheline as the main feldspathoid; ... The extrusive equivalent of nepheline., fonoliit - nefeliinsüeniitide porfüürilise või afüürilise struktuuriga vulkaaniline analoog, mis löögist heliseb. Koosneb leeliselistest päevakividest, feldšpatoididest (nefeliin, leutsiit jt.), amfib