Petrographic analysis of the ophite outcrop on the right bank of the Ariege river, below Vebre, France, shows that the rock is rich in epidote and exhibits pegmatoid differentiation. Three rock types are distinguished--common ophite with variable amounts of epidote; ophite with phlogopite; and pegmatoid rocks with orthoclase. The results of four chemical analyses indicate that the Vebre ophites were affected by pneumatolysis during crystallization from a saturated basaltic magma. The pneumatolysis caused the crystallization of hornblende and, in a later phase of potassium enrichment, the superimposition of orthoclase in the pegmatoid plagioclases and the phlogopite in the hornblende crystals of the ophite.

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