Doyleite

minerals

montroyalite

gibbsite

dawsonite

Images
Formula: Al(OH)3
Hydroxide, perimorph of bayerite, gibbsite and nordstrandite
Specific gravity: 2.48
Hardness: 2½ to 3
Streak: White
Colour: White, creamy-white, bluish-white
Solubility: Insoluble in cold mineral acids (Dana)
Environments

Plutonic igneous rocks
Hydrothermal environments

Doyleite is a late-stage hydrothermal mineral lining vugs in veins in nepheline syenite (Webmin).

Localities

There are two co-type localities, the Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, and the Francon quarry, both in Quebec, Canada.

At the Poudrette quarry, doyleite occurs as a late-stage hydrothermal mineral lining vugs in albite-rich veins in a nepheline syenite pegmatite associated with an intrusive alkalic gabbro - syenite complex. Associated minerals include calcite, albite and pyrite (HOM, Dana, AM 71.845 ).

At the Francon quarry doyleite occurs sparingly in vugs within silicocarbonate sills intruding limestone. It is a late stage mineral forming aggregates on cryolite, weloganite, strontianite and calcite crystals. Other associated minerals include albite, baryte, dresserite, hydrodresserite, strontiodresserite, quartz, dawsonite, fluorite, analcime, halloysite and montroyalite. Doyleite admixed with gibbsite commonly forms perimorphs after cryolite (Minrec 37.1.31, AM 71.845).

At the Saint-Amable sill, Varennes & St-Amable, Lajemmerais RCM, Montérégie, Quebec, Canada, doyleite occurs in miarolitic cavities in a nepheline syenite sill, associated with microcline, eudialyte, yofortierite, astrophyllite, serandite, aegirine, cryolite and gibbsite (HOM, Minrec 37.1.31).

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