These are the rocks formed in a typical geothermal gradient of about 25 C per km. The normal sedimentary assemblage in carbonate rocks. This is the same reaction as above, except this one extracts the magnesium component from dolomite. At about 500 C, talc, calcite and quartz react to form tremolite.
Calcite can coexist with talc only under extremely restricted conditions.
The marginal compatibility of calcite and talc ends completely as calcite plus talc react to give tremolite plus dolomite. O. Note that talc is becoming progressively less compatible with carbonates. Dolomite and talc can no longer coexist as dolomite plus talc react to give tremolite plus forsterite. Note that talc now cannot coexist with any carbonates. O Note how the stability fields of dolomite are shrinking with each reaction.