Quintinite

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Formula: Mg₄Al₂(OH)₁₂(CO₃).3H₂O
Hydrated carbonate containing hydroxyl, quintinite group
Crystal System: Hexagonal
Specific gravity: 2.14 measured, 2.15 calculated
Hardness: 2
Streak: White
Colour: Yellow to colourless, orange-brown
Luminescence: Not fluorescent
Environments

Pegmatites
Carbonatites
Hydrothermal environments

Quintinite is found as both 2H and 3T polytypes. Both polytypes were originally approved as separate species, but since 1998 polytypes are not considered as separate species anymore (Mindat).

Localities

There are two co-type localities, the Jacupiranga Alkaline Complex, Cajati, São Paulo, Brazil, and the Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada.

At the Jacupiranga Alkaline Complex, Cajati, São Paulo, Brazil, quintinite-2H occurs in vugs in dolomitic carbonatite, and is associated with dolomite, magnetite, fluorapatite, phlogopite, pyrite, calcite, chalcopyrite and pyrrhotite (CM 35.1541-1549).

The Mount Mather Creek claim, Golden Mining Division, British Columbia, Canada, is a sodalite-bearing breccia dyke that consists of carbonate-rich syenite segregations that occur as veins and pods, and fine-grained banded sodalite plus carbonate fragments in a carbonate-rich matrix. The sodalite-carbonate segregations consist dominantly of sodalite, iron-bearing dolomite, calcite and microcline, with an extensive suite of trace minerals including albite, analcime, ancylite-(Ce), chabazite-Na, fluorapatite, baryte, barytocalcite, cancrinite, galena, goethite, gonnardite, harmotome, edingtonite, natrolite, nordstrandite, pyrite, quintinite and sphalerite (MM 86.2.282-306).

At the Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada, quintinite-3T was found in the alkaline complex as a late-stage hydrothermal mineral in miarolitic cavities and in pegmatitic bodies within nepheline syenite. Associated minerals include analcime, natrolite, aegirine, calcite, siderite, fluorite, pyrite, biotite, donnayite-(Y) and ancylite-(Ce). In another occurrence, trace amounts of quintinite-3T were identified in aggregates of muscovite crystals (CM 35.1541-1549).

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