Montroyalite

minerals

doyleite

strontiodresserite

dawsonite

Formula: Sr4Al8(CO3)3(OH)26.10H2O
Hydrated carbonate containing hydroxyl
Specific gravity: 2.677
Hardness: 3½
Streak: White
Colour: White
Solubility: Soluble in 1:1 hydrochloric acid (AM 72.1025)
Environments

Carbonatites

Localities

The only known locality to date (September 2020) is the type locality, the Francon quarry, Montréal, Québec, Canada, where montroyalite occurs as white translucent hemispheres to 1 mm in cavities in an exposed silicocarbonatite sill, and as individual grains. Associated minerals include albite, quartz, strontiodresserite, calcite, dawsonite, ankerite, fluorite, baryte, strontianite, smythite, marcasite, pyrite, halloysite and doyleite (AM 72.1025, HOM, Mindat). Montroyalite is a late stage mineral, and it is invariably and intimately associated with strontiodresserite (Minrec 37.1.39-40)

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