Pegmatites,which Often Occur in Dikes,are Unusual Among Shallow Intrusive Rocks

Multiple Choice

Pegmatites,which often occur in dikes,are unusual among shallow intrusive rocks in that they ________.

A) possess porphyritic texture
B) possess exceptionally coarse grains
C) are mineralogically identical to the extrusive rock basalt
D) are glassy,cooling so rapidly that crystals do not have time to form