AENIGMATITE
AENIGMATITE Aenigmatite – Na4[Fe2+10Ti2]O4[Si12O36] – is a very rare inosilicate similar to amphiboles (same habits). It has no economic importance. It is classified in the Sapphirine Supergroup, Aenigmatite Group, forming a series with wilkinsonite. May contain Mn, Mg, Ca, K, Cl and Al as impurities. Aenigmatite is related to malakhovite. 1. Characteristics Crystal system: Triclinic […]
AEGIRINE-AUGITE
AEGIRINE-AUGITE Aegirine-augite is an inosilicate of the Pyroxene Group. It is a rarer mineral, typical mainly of some alkaline igneous rocks. It has no importance as an ore. It is not considered a mineral species, but only an intermediate term between aegirine and augite, which form a series in the Pyroxene Group, Clinopyroxene Subgroup. For […]
AEGIRINE
AEGIRINE Aegirine is an inosilicate of the Pyroxene Supergroup. It is an uncommon mineral, whose occurrence is restricted to some types of rocks. It has no economic importance. Aegirine forms a solid solution with augite. The middle term is aegirine-augite. “Acmite” was a term used for both green and brown aegirines with pointed ends; the […]
ACANTHITE
ACANTHITE Acanthite – Ag2S – is a rarer sulfide typical of hydrothermal veins. It is the most important silver ore after argentiferous galena. Acanthite and argentite are polymorphs. Silver sulfide can form at more than 177ºC (literature diverges: 173ºC, 179ºC, 180ºC) with cubic structure or below this temperature with monoclinic structure. The mineral with a […]