Ankerite

ANKERITE (from the name of the Austrian mineralogist Matthias Anker * EN: ankerite; DE: Ankerit; FR: ankerite; ES: anquerita; RU: анкерит) is the mineral of the class of carbonates, Ca(Mg,Fe2+)[CO3]2. Commonly ratio Mg:Fe2+ is 1:1, ratio (Mg+ Fe2+):Ca is from 1:1 to 3:1.

It often contains Mn. It crystallizes into the trigonal crystal system; there are at the foundation of the crystal structure the triangular anion radicals [CO3]2-. It is analogous to dolomite according to the shape of crystals and aggregates. The colour is white, yellowish, brown, pink, gray, and blue. The hardness is 3.5; it is brittle. The density is 3000±100 kilograms per cubic metre. It is the typical mineral of carbonatites and low-temperature lead-zinc deposits within the carbonatic rocks (with barite, fluorite, dolomite).

It is known within the rock crystal alpine veins, and as the product of metasomatism within the carbonatic sediments. It forms nodules and pseudomorphs along the organic residues within the sedimentary strata. It may be found within the certain metamorphic rocks.