The deep-zone minerals are not unlike the pegmatite minerals in their grouping and associations.
"The Economic Aspect of Geology"
C. K. Leith
Tungsten is likewise found in original segregations in igneous rocks and in pegmatite dikes, but these deposits are of comparatively small commercial importance.
"The Economic Aspect of Geology"
C. K. Leith
The Virginia production comes from pegmatite dikes cutting through gabbros, syenites, and gneisses.
"The Economic Aspect of Geology"
C. K. Leith