Katoite

katoite

stratlingite

tobermorite

afwillite

Images

Formula: Ca3Al2(OH)12
Hydroxide, ungrouped member of the garnet supergroup, forms a series with grossular
Crystal System: Isometric
Specific gravity: 3.013 calculated
Hardness: 5 to 6
Streak: White
Colour: Colourless
Luminescence:
Solubility:
Common impurities: Mg,S
Environments

Volcanic igneous environments
Hydrothermal environments

Localities

At the Csódi Hill, Dunabogdány, Szentendre District, Pest County, Hungary, katoite has been found with about 37% grossular (EJM 15.419-426).

At the type locality, the Campomorto Quarry, Pietra Massa Locality, Montalto di Castro, Viterbo Province, Lazio, Italy, katoite occurs as a hydrothermal mineral in cavities in a phonolitic lava flow that erupted through an argillaceous marl. Associated minerals include tobermorite, afwillite, gehlenite, hydrocalumite, opal, portlandite, apophyllite, cordierite, jennite, strätlingite, chabazite, gismondine-Ca, phillipsite, vertumnite, ettringite, garnet, wollastonite, gypsum, calcite, quartz and hematite (HOM).

Katoite from the Campomorto Quarry - Image

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