Glaucochroite

Glaukochroit is a rarely occurring mineral from the mineral class of " silicate and germanate ". It crystallizes in the orthorhombic crystal system with the chemical composition CaMn2 [ SiO4 ] and usually develops granular to massive mineral aggregates, rarely prismatic crystals up to 1 cm length of mainly bluish green color. Also, pink, white and brown Glaukochroite are known.

Etymology and history

Was first found in 1899 in the Glaukochroit the " Franklin Mine" in Franklin ( NJ ) in Sussex County of New Jersey in the United States. Was scientifically described the mineral from Samuel Lewis Penfield (1856-1906) and CH Warren, the γλαυκός it after the Greek words ( Glaucus ) "bright", " bright ", " brilliant "; the sea concerning: " (gray) bluish " and χρώμα ( chroma ) "Color"

Classification

In the old ( 8th edition ) and new classification of minerals according to Strunz ( 9th edition ) of the Glaukochroit belongs to the department of the " island silicates ( nesosilicates ) ". He, together with Kirschsteinite and monticellite own group.

The revised 9th edition of the Strunz'schen Mineral classification divides this department, however, precisely according to the presence or absence of other anions and the coordination of the cations involved. The Glaukochroit is thus in accordance with the division of the " island silicates without additional anions; with cations in oktahedraler coordination " and there was to be yet another member of the olivine group.

The commonly used in English-speaking classification of minerals according to Dana assigns the Glaukochroit similar to the new Strunz'sche Mineral classification in the department of " island silicates: SiO4 groups with all cations only in oktahedraler coordination " where the mineral is also together with Kirschsteinite and monticellite forms an independent group that monticellite - Kirschsteinite series.

Education and Locations

Glaukochroit forms metamorphic layered zinc deposits in skarns as contact metamorphism between diabase and marble or limestone Silicatgesteinen with manganese ores. It occurs there in paragenesis on with various minerals such as andradite, calcite, cuspidine diopside, Esperit, Franklinite, hardystonite, Hodgkinsonit, Klinoedrit, Leukophönicit, Nasonit, tephroite, willemite and zincite.

Apart from its type locality " Franklin Mine" in New Jersey (USA) Glaukochroit has not been proven to 5 other localities: In the " Kanoiri Mine" at Kanuma on the Japanese island of Honshu; in the " Kombat Mine" at Kombat in the Namibian region Otjozondjupa; in the Khibiny Massif on the Russian Kola Peninsula; in the " Wessels Mine " at Hotazel ​​in the South African Kalahari; and in the " Jacob Mountain Mine" at Nordmark in the Swedish municipality Filipstad.

Crystal structure

Glaukochroit crystallizes in the orthorhombic space group Pbnm with lattice parameters a = 4.913 Å; b = 11.151 Å and c = 6.488 Å and four formula units per unit cell.