Mineral Environments
- Altered Pegmatites -

     "The pegmatites, which are the residual portion of the magma and the last to have crystallized, can take the form of dikes, pipes and lenses. They appear to have no continuation at depth. Many of them pinch and swell irregularly from a few centimeters to a meter or more in width. Where the pegmatites swell, open cavities occur with well formed crystals growing in the cores. Included under pegmatites are small, coarse grained patches and segregations in nepheline syenite".*

     "The syenitic pegmatites of MSH generally are rich in sodium silicates and rare element minerals" (Table a - Unaltered pegmatites). "The most common minerals of the pegmatites are microcline and aegirine with local concentration of analcime, sérandite and catapleiite. Many of the pegmatites are altered in varying degrees, probably by hydrothermal action. These are characterized by manganese oxides, chlorites, sulfides and other minerals" (Table b - Altered pegmatites).*

* From Mineralogical Record Vol 21, Horváth L. and Gault R.A.