Century Dictionary and Cyclopedia
- n tephrite The name of certain modern volcanic rocks of rather varied and uncertain composition. The tephrites bear the same relation to the normal basalts that the phonolites do to the trachytes (Rosenbusch). Among the older eruptive rocks, theralite is the representative of tephrite, the essential features of which are that it is porphyritic in structure, the ground-mass containing a soda-lime feldspar, which also sometimes occurs in distinct crystals, while to this are added nephelin, leucite, and augite, with apatite, magnetite, and other less abundant minerals. See nephelin-tephrite and leucite-basalt.
Chambers's Twentieth Century Dictionary
- n Tephrite tef′rīt a name applied to certain modern volcanic rocks