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A porphyritic extrusive rock having phenocrysts of plagioclase and
potassium feldspar in nearly equal amounts, little or no quartz, and a
finely crystalline to glassy groundmass, which may contain obscure
potassium feldspar; the extrusive equivalent of monzonite. Latite grades
into trachyte with an increase in the alkali feldspar content, and into
andesite or basalt, depending on the presence of sodic or calcic
plagioclase, as the alkali feldspar content decreases. It is usually
considered synonymous with trachyandesite and trachybasalt, depending on
the color. The name, given by Ransome in 1898, is derived from Latium,
Italy. AGI
Source:
Dictionary of Mining, Mineral, and Related Terms
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