Images
Formula: Na6(Al6Si10O32).8.5H2O
Tectosilicate (framework silicate), zeolite group, forms a series with
garronite-Ca, previously known as
garronite
Crystal System: Monoclinic
Specific gravity: 2.19 measured, 2.071 calculated
Hardness: 4
Streak: White
Colour: Pale yellow to white
Environments
Plutonic igneous rocks
Hydrothermal environments
Basalt cavities
Garronite-Na is a relatively new mineral, approved in 2015.
Localities
At the type locality, the Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Quebec, Canada,
garronite-Na occurs in vugs in sodalite
syenite as botryoidal masses up to 1.5 mm in size. Associated minerals include
aegirine, natrolite,
gmelinite and gonnardite
(CM 54.1549-1562).
At Shiratobana, Hirado Island, Hirado City, Nagasaki, Japan, silica-rich garronite-Na was found in a cavity with a
diameter of about 2 mm in altered basaltic rock. Hirado Island is composed
mainly of volcanic andesite and
basalt lava accompanied by pyroclastic rocks. More than 10 species of
zeolite (chabazite,
epistilbite, harmotome,
phillipsite, stellerite,
stilbite, barrerite,
thomsonite, scolecite,
mordenite, dachiardite and
ferrierite) have been described as occurring in altered volcanic rocks from the
Island. The zeolite minerals occur as hydrothermal minerals in the druses and veins
of the basaltic and andesitic
rocks. The garronite-Na from Shiratobana fills the central part of the cavity and is associated with radial
aggregates of epistilbite, which cover the inside of the cavity, suggesting that
the garronite-Na crystallised after the formation of the epistilbite
(CM.60.1.91-99).
Back to Minerals