retinite

RET'INITE, n. [Gr. resin.] Pitchstone; stone of fusible pitch, of a resinous appearance, compact, brown, reddish, gray, yellowish, blackish or bluish, rarely homogeneous, and often containing crystals of feldspar and scales of mica. It is the pechstein porphyry or obsidian of the Germans. It is called also retinasphalt.