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Hydrothermal reactivity of saponite

Clays and Clay Minerals

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https://doi.org/10.1346/CCMN.1983.0310101

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Abstract

Saponite crystallizes from amorphous gel having an ideal saponite composition within 7 days at all experimental temperatures between 300° and 550°C at 1 kbar pressure. Reactions subsequent to this initial crystallization vary in type and degree, depending on the temperature of reaction and the type of interlayer cation. Above 450°C the intitially crystallized K-saponite dissolves, and talc and phlogopite nucleate and grow as discrete phases. At 450°C the initial K-saponite reacts to form talc and phlogopite layers, but the reaction proceeds via intracrystalline layer transformations rather than via dissolution and precipitation, producing a mixture of fully ordered, interstratified talc/saponite and fully ordered saponite/ phlogopite. The K-saponite shows subtle signs of reaction at 400°C after 200 days: this temperature is at least 150°C lower than experimental reaction temperatures previously reported for saponites. No reactions beyond the initial crystallization of saponite were observed below 400°C. K-saponite reacts more rapidly than either Na-saponite or Ca-saponite above 400°C and the Na-saponite and Ca-saponite produce no mica iayers during their transformation to mixed-layer clays. Interstratified talc/saponite formed in the Na-saponite system, and the Ca-saponite system produced both talc/saponite and chlorite/saponite.

Additional publication details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Hydrothermal reactivity of saponite
Series title:
Clays and Clay Minerals
DOI:
10.1346/CCMN.1983.0310101
Volume:
31
Issue:
1
Year Published:
1983
Language:
English
Publisher:
The Clay Minerals Society
Description:
8 p.
First page:
1
Last page:
8