Ankerite

A very aesthetic sample of ankerite originating from Shangbao. Floater of hypoparallel confluence of crystals. The edge of the largest crystals has size 63 mm.

Ankerite

It was named after Mathias J. Anker (1771-1843), an Austrian mineralogist. It is white or yellowish. They usually form granular aggregates or well-limited arch crystals. It occurs on hydrothermal veins, on iron ore deposits (siderite) and in sedimentary rocks.

• Chemical Formula: Ca(Fe++,Mg,Mn)(CO3)2
• Molecular Weight: 206.39 gm
• Environment: Common in ore-bearing rocks as a rock forming mineral (gangue). High Fe species are found in iron ores.
• IMA Status: Valid Species (Pre-IMA) 1825
• Locality: Styrian Erzberg, Eisenerz, Styria, Austria
• Synonym: Brown Spar

Composition:

• Calcium: 19.42 %  Ca, 27.17 % CaO
• Magnesium: 3.53 %  Mg, 5.86 % MgO
• Manganese: 2.66 %  Mn, 3.44 % MnO
• Iron: 16.24 %  Fe, 20.89 % FeO
• Carbon: 1.64 %  C, 42.65 % CO2
• Oxygen: 46.51 %  O

Physical Properties:

• Cleavage: {1011} Perfect, {1011} Perfect, {1011} Perfect
• Color: Brown, Brownish yellow, Gray, Gray brown, White.
• Density: 3 - 3.1, Average = 3.05
• Diaphaneity: Translucent to subtranslucent
• Fracture: Sub Conchoidal - Fractures developed in brittle materials characterized by semi-curving surfaces.
• Habit: Crystalline - Coarse - Occurs as well-formed coarse sized crystals.
• Habit: Granular - Generally occurs as anhedral to subhedral crystals in matrix.
• Habit: Massive - Uniformly indistinguishable crystals forming large masses.
• Hardness: 3.5-4 - Copper Penny-Fluorite
• Luminescence: Non-fluorescent.
• Luster: Vitreous (Glassy)
• Streak: white