Formula: PbSiO3
Inosilicate (chain silicate)
Specific gravity: 6.49
Hardness: 4½
Streak: White
Colour: Colourless to white
Solubility: Gelatinises with acids
Common impurities: Al,Fe,Mn,Ca

Hydrothermal environments

Alamosite is a rare secondary mineral found in the oxidised zone of lead-bearing deposits (R&M 96.2.158-163).


At the San Pascual Mine, Zimapán, Mun. de Zimapán, Hidalgo, Mexico, alamosite is associated with anglesite, cerussite and wulfenite (R&M 96.2.160).

At the type locality, Álamos, Álamos Municipality, Sonora, Mexico, alamosite is associated with wulfenite, leadhillite and cerussite (HOM).

At the Tsumeb mine, Tsumeb, Oshikoto Region, Namibia, alamosite crystals are far superior to those from the type locality. One fine specimen was found to have a 15 mm crystal of plumbotsumite attached. Another specimen has been examined in which leadhillite and anglesite grew on an encrustation of hematite and mimetite crystals, lining a vug in ore comprising galena, germanite, tennantite and a little quartz. Alamosite rested directly on the mimetite/hematite and clearly predated the anglesite and leadhillite. Also predating the anglesite were rare crystals of fleischerite. Both the anglesite and the leadhillite were spotted with melanotekite, and flakes of kegelite were found on some of the anglesite. Alamosite is usually the oldest of the lead silicate minerals here, but examples of alamosite overgrowing and including melanotekite are also known (R&M 96.2.158-163).

At the Lucky Cuss Mine, Cochise County, Arizona, USA, alamosite occurs as spherical aggregates of radiating crystals associated with quartz, queitite and zeolites (R&M 96.2.158).

At the Rawhide Mine, Rawhide Wash, Artillery Mountains, Mohave county, Arizona, USA, alamosite is associated with melanotekite, shattuckite and wickenburgite (HOM). Other associates include hyalotekite, cerussite, chrysocolla, malachite, mimetite and wulfenite (R&M 96.2.159).

At Tiger, Mammoth Mining District, Pinal county, Arizona, USA, alamosite is associated with diaboleite, phosgenite, cerussite, wulfenite and willemite (HOM).

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