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Formula: (Ca,Na,Mg)2(Si,Al)12O24.15H2O
Tectosilicate (framework silicate), faujasite subgroup,
zeolite group
Crystal system: Isometric
Specific gravity:
Hardness: 5
Environments
Volcanic igneous environments
Hydrothermal environments
Localities
At the Limberg Quarries, Sasbach am Kaiserstuhl, Emmendingen, Freiburg Region, Baden-Württemberg, Germany, there is
a scarcity of clay in the vesicles and fractures in the host
limburgite. The faujasite here preceded
offretite and phillipsite
(AM 67.794-798).
Faujasite-Ca from the Limberg Quarries -
Image
At the type locality, Haselborn, Ilbeshausen, Grebenhain, Vogelsbergkreis, Giessen Region, Hesse, Germany,
faujasite is associated with offretite, which was not found at the
California locality, and with phillipsite. Where it is in contact with
faujasite, the phillipsite grew later
(AM 67.794-798).
At Palagonia, Metropolitan City of Catania, Sicily, Italy, faujasite is a minor associate of later-grown
chabazite-Na and
phillipsite. The faujasite in the
palagonitised tuff
grew directly on the walls of vesicles
with no precursor clay, and was followed by
phillipsite
(AM 67.794-798).
Faujasite-Ca from Palargonia -
Image
At the Table Mountain Zeolite occurrence, Squaw Mountain, Shadow Mts, San Bernardino County, California, USA, the
volcano with the faujasite-bearing tuffs is the northernmost in
the lava field that lies on the western flank of the Cima Dome. Vents in the lava field are characterised by cinder
cones, the older ones of which are substantially eroded. The section 16 volcano apparently erupted in a major
drainage, where more than 100 m of cinders, consisting of basaltic
glass, were deposited on granitic gravels. Water saturated the lower
two-thirds of this accumulation, converting the basaltic glass to
palagonite. The upper third was partially altered to
clay and hematite, colouring
the pile red.
The zeolites occur in vesicles in the
palagonitised
pyroclastic sediment and as very thin crusts at the base of
the reddened pyroclastic sediment. Faujasite and
phillipsite occur sparingly in the cavities of the
pyroclastic sediment, filling less than 25% of the void volume. Faujasite is
most abundant near the top of the palagonitised section, but is
present sparingly throughout. In contrast to most zeolite occurrences,
these were not preceded by clay minerals. Many bombs greater than 10 cm
across remain unaltered and contain zeolites only in surface cavities. The
total volume of faujasite is probably not greater than 10% of the volume of
phillipsite.
Faujasite occurs as water clear octahedra as much as 0.75 mm across. The crystals are commonly intergrown and
twinned on the spinel law.
Phillipsite occurs as radiating, twinned prisms in clusters as much as
1 mm across. Where it is in contact with faujasite, the
phillipsite grew later. Unlike the German localities,
offretite was not found at the California locality.
The distribution of faujasite can be interpreted as having crystallised early while the water was most
dilute. Phillipsite crystallised later and deeper in the pile where
salinities were greater
(AM 67.794-798).
Faujasite-Ca from the Table Mountain Zeolite
Locality - Image
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