Sorosilicate (Si2O7 groups)
Specific gravity: 4.43
Hardness: 3 to 4
Colour: Lemon to canary yellow
Solubility: Insoluble or only slightly soluble in most cold dilute acids and bases; it is decomposed by hot 1:1 hydrochloric acid and cold glacial (anhydrous) acetic acid. It is partially melted when heated to 1200oC, and completely melted at 1300oC to a yellow glass (AM 50.335).
Common impurities: Al,Fe,Mn,Mg,Ca,Sr,K
At the Gun claim, Wilson Lake, Itsi Mountain, Watson Lake mining district, Yukon, Canada, fresnoite occurs with gillespite, sanbornite, taramellite, pellyite, muirite and baryte (HOM).
At the Esquire No. 1 claim, Rush Creek, Rush Creek deposit, Big Creek-Rush Creek Mining District, Fresno county, California, USA, fresnoite occurs with bario-orthojoaquinite, benitoite, baotite and natrolite (HOM).
At the type locality, the Esquire No. 7 claim, Big Creek, Rush Creek deposit, Big Creek-Rush Creek Mining District, Fresno county, California, USA, fresnoite occurs in sanbornite-bearing metamorphic rocks which outcrop in a narrow zone near a granodiorite contact, and in quartzite that is poor or lacking in sanbornite. Locally it is concentrated in thin layers in quartzite associated with celsian, taramellite, diopside and pyrrhotite. The individual grains are generally less than 1 mm long (AM 50.314-340).
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