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Formula: Ca3(Si30Al6)O72.20H2O
Hydrated tectosilicate (framework silicate),
clinoptilolite subgroup,
zeolite group
Crystal system: Monoclinic
Specific gravity:
Hardness: 3½ to 4
Colour: Colourless to white, pale orange
Solubility: Readily decomposed by hydrochloric acid
Common impurities: Na,K
Environments
Clinoptilolites most commonly form as devitrification products of silicic volcanic glass from
tuffs. They also occur in cavities in
rhyolites and more-mafic
rocks such as andesites and
basalts. Often present in saline, alkaline lake sedimentary deposits
derived from volcanic material. Commonly associated with other zeolites,
montmorillonite,
hectorite, quartz,
opal, calcite and
K-feldspar. Other minerals that may be associated are
halite, celadonite,
gaylussite and thenardite
(Dana).
Localities
The type locality is the Kuruma Pass, Fukushima Prefecture, Japan.
At the Cape Lookout Quarry, Netarts, Tillamook County, Oregon, USA, clinoptilolite-Ca has been found with
mordenite
(Mindat photo).
Clinoptilolite-Ca from the Cape Lookout Quarry -
Image
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