Marble

Marble is a metamorphic rock formed when limestone or dolostone recrystallizes under heat and pressure, giving a sugary mosaic of interlocking calcite or dolomite crystals. Pure marble is white, and impurities add veins of other colors.

🪨 Geology Guide Specimen: Open Crystalline Marble in the CRV Science Rock & Mineral ID Guide to log the specimen, compare it with the other 6 subgroups of Metamorphic, and test your eye in LithoClade.

Heat, from a nearby intrusion or from deep burial, makes the small grains of fossiliferous limestone or chalk grow into larger interlocking crystals. The fossils and bedding are mostly erased. Marble is soft, Mohs 3, so a steel knife scratches it, and it fizzes in dilute acid.

Graphite makes marble grey, hematite pink and serpentine green, and veins reflect minerals that formed in the original limestone or grew from other minerals during metamorphism. Some marbles contain visible silicates such as diopside or tremolite.

Fine-grained white marble is easy to carve and translucent, so it was used for Greek and Roman sculpture and buildings. The Parthenon is built of Pentelic marble and Michelangelo's David was carved from Carrara marble. Because calcite dissolves in acid, marble monuments are damaged by acid rain.

• Fossiliferous Limestone — a common parent rock
• Dolostone — the parent of dolomitic marble
• Calcite — the mineral that makes most marble