Marble (Dolomitic)
“Metamorphosed dolostone with magnesium minerals”
Dolomitic marble forms when dolostone (rather than limestone) undergoes metamorphism, producing a rock dominated by dolomite crystals rather than calcite. At higher metamorphic grades, the dolomite reacts with silica impurities to produce distinctive magnesium-rich minerals like forsterite, tremolite, and diopside.
dolomite, calcite, forsterite, tremolite, diopside, phlogopite, spinel
Carrara (Italy — some varieties), Adirondacks (New York, USA), Bancroft (Ontario, Canada), Sri Lanka, Mogok (Myanmar)
3.5-4
The reaction of dolomite with quartz at metamorphic temperatures produces the minerals tremolite, then diopside, then forsterite — a sequence so well-understood that it's used in petrology textbooks worldwide as a classic example of progressive metamorphic reactions.
Test Your Knowledge
What progressive metamorphic reaction sequence occurs when dolomitic marble is heated in the presence of silica?
Related Specimens
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