saussurite

geology

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July 23, 2026

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Saussurite is a mineraloid formed from the alteration of calcium-bearing plagioclase feldspar. This process, known as saussuritization, typically results in a mixture of zoisite, chlorite, amphibole, and carbonates. It can occur during the late stages of magmatic crystallization or through later hydrothermal alteration. Saussuritization is particularly common in mafic rocks due to their high calcium content, but it can also affect calcium-rich portions of plagioclase in acidic rocks. The resulting substance is tough, compact, and can be white, greenish, or grayish.12

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saussuritization
…characteristic assemblage of minerals called saussurite; the typical assemblage formed includes zoisite, chlorite, amphibole, and carbonates. Residual fluids present during the late stages of magmatic crystallization can react with previously formed plagioclase feldspar to form saussurite; the saussurite will be spread through the plagioclase or located near its outer margin.…
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…characteristic assemblage of minerals called saussurite; the typical assemblage formed includes zoisite, chlorite, amphibole, and carbonates. Residual fluids present during the late stages of magmatic crystallization can react with previously formed plagioclase feldspar to form saussurite; the saussurite will be spread through the plagioclase or located near its outer margin.…
Read More