Photomicrograph of gabbro from Mt. Megantic, Monteregian Hills, 40X, crossed-polars

Igneous and Metamorphic Petrology Laboratory
 89.506

 

 

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Michel-Levy.jpg (89626 bytes) Carlsbad-albite.jpg (95241 bytes) Modal percent chart.jpg (89354 bytes)  
Michel-Levy law for determining plagioclase composition. From Kerr (1959) Carlsbad-albite twin law for determining plagioclase composition. From Kerr (1959) Chart for determining modal percentage. From Philpotts (1989)  

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