Anhydrous acid phosphate
Specific gravity: 2.58 calculated
Hardness: 1 to 2
Solubility: Extremely soluble in water and, to a much lesser extent, in concentrated hydrochloric acid (AM 67.856-857)
Plutonic igneous environments
Nahpoite occurs in sodalite xenoliths and in late-stage phosphatian
and halogen alterations in alkalic syenite. Associated minerals include
natrophosphate, sodalite and
At the Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Quebec, Canada, nahpoite occurs in sodalite xenoliths associated with an intrusive alkalic gabbro-syenite complex (HOM).
At the type locality, Big Fish River, Dawson mining district, Yukon, Canada, nahpoite occurs in nodules in phosphatic ironstone with marićite and satterlyite (AM 67.856-857, Dana) At the Lovozersky District, Murmansk Oblast, Russia, nahpoite occurs in differentiated alkalic massifs associated with natrophosphate and villiaumite (HOM).
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