Les W
Active member
Taken directly from the Collins Dictionary of Geology:
"Limestone, n. A sedimentary rock composed almost entirely of calcium carbonate (CaCO3), mainly as CALCITE."
It goes on to list various types of limestone and under Organic Limestones it says that these consist of shell remnants or of calcite precipitated by certain algae eg. coral limestone, crinoidal limestone, chalk.
Listed under CHALK it gives:
"Chalk, n. a soft, earthy, fine-grained white to greyish LIMESTONE of marine origin, composed almost entirely of biochemically derived calcite.
:read:
"Limestone, n. A sedimentary rock composed almost entirely of calcium carbonate (CaCO3), mainly as CALCITE."
It goes on to list various types of limestone and under Organic Limestones it says that these consist of shell remnants or of calcite precipitated by certain algae eg. coral limestone, crinoidal limestone, chalk.
Listed under CHALK it gives:
"Chalk, n. a soft, earthy, fine-grained white to greyish LIMESTONE of marine origin, composed almost entirely of biochemically derived calcite.
:read: