The hills on which I stood were composed of pegmatite, with patches of white Mica in large leaflets.
The specimen was taken from a pegmatite dike at its contact with an amphibolite.
Granite and pegmatite were round some lagoons near the creek from the southward.
Pebbles and blocks of pegmatite covered the bed of the creek.
Connected with the borolanite there are other types of nepheline-syenite and pegmatite.
The deep-zone minerals are not unlike the pegmatite minerals in their grouping and associations.
The granite, which is intruded through the Eocene beds, is associated with a pegmatite containing tourmaline and cassiterite.
The Virginia production comes from pegmatite dikes cutting through gabbros, syenites, and gneisses.
In North Carolina sapphire has been found in pegmatite dikes.
Some of the graphite also occurs in pegmatite intrusives and adjacent wall rocks.
Any of various coarse-grained igneous rocks that often occur as wide veins cutting across other types of rock. Pegmatites form from water-rich magmas or lavas that cool slowly, allowing the crystals to grow to large sizes. Although pegmatites can be compositionally similar to a number of rocks, they most often have the composition of granite.