Ettringite
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Ettringite is a hydrous calcium aluminium sulfate mineral with formula: Ca6Al2312·26H2O. It is a colorless to yellow mineral crystallizing in the trigonal system. The prismatic crystals are typically
Ettringite, Kalahari manganese fields, Northern Cape Province, South Africa
Ettringite, 6.5 × 3.2 cm. N'Chwaning Mines, Kalahari manganese fields, Northern Cape Province, South Africa
SEM image of fractured hardened cement paste, showing thin hexagonal plates of portlandite (calcium hydroxide) and needles of ettringite (micron scale)
Fibroradiated ettringite needles on slag (Concordia smelter, Eschweiler, Aachen, Germany)
Portlandite
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Portlandite is a hydroxide-bearing mineral typically included in the oxide mineral class. It is the naturally occurring form of calcium hydroxide and the calcium analogue of brucite.
Ettringite
…intrusive rocks or within xenoliths. It also occurs as weathering crusts on larnite in the Hatrurim Formation of Israel. It occurs associated with portlandite, afwillite and hydrocalumite at Scawt Hill, Ireland and with afwillite, hydrocalumite, mayenite and gypsum in the Hatrurim Formation. It has also been…
Portlandite and ettringite