Abstract

Small pegmatites in Griffith Township, Ontario, contain chiefly quartz, microcline, plagioclase, pyroxene, and sphene, and accessory hornblende, biotite, apatite, allanite, zircon, scapolite, chlorite, calcite, pyrite, and molybdenite. The dikes are weakly to moderately radioactive, which stems chiefly from the sphene and allanite and to a lesser extent from the apatite and zircon. Paragenetic relations indicate that microcline began to crystallize first and that most of the augite is relatively late. The pegmatites are also geochemically peculiar, both in the abundance of Ca-bearing minerals they contain despite their general granitic character, and their content of accessory elements, Ti, Ce, PO 4 , and CO 3 . They differ from other well-known sphene-bearing dikes in the region in the near-absence of zircon and the relative abundance of allanite.

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