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Ferrierite comprises four minerals:
Ferrierite-K,
(K,Na)5(Si31Al5)O72.18H2O
Ferrierite-Mg,
[Mg2(K,Na)2Ca0.5](Si29Al7)O72.18H2O
Ferrierite-Na,
(Na,K)5(Si31Al5)O72.18H2O
Ferrierite-NH4,
(NH4,Mg0.5)5(Al5Si31O72).22H2O
They are tectosilicate (framework silicates), ferrierite subgroup,
zeolite group
Specific gravity: 2.06 to 2.23
Hardness: 3 to 3½
Streak: Mg: White
Colour: Ferrierite-Mg: Colourless, white, pink, orange, red due to Fe3+
Environments:
Metamorphic environments
Sedimentary environments
Basaltic cavities
Ferrierite is a fairly rare zeolite, mostly occuring in cavity fillings in
basalt or andesite, and as a
diagenetic mineral in
rhyolite tuff, as a result of
hydration reactions. It also occurs in metamorphic rocks. In all occurrences ferrierite is closely associated with other
high-silica zeolites, commonly mordenite and
clinoptilolite, as well as opal or
chalcedony and calcite. Temperatures of formation
range from the surface conditions of lakes in arid climates to that of weak hydrothermal systems (120o to
150oC)
(Dana, Webmin, IZA).
Ferrierite-Na occurs in seams and vesicles in deeply weathered basalt, flow
breccias, and andesite; also in
tuffaceous sediments. Associated minerals include
zeolites, plagioclase,
enstatite-ferrosilite,
augite,
montmorillonite, chalcedony
and calcite
(HOM).
Localities
in the tunnels through Tanzenberg near Kapfenberg, Styria, Austria, ferrierite with
mordenite and
dachiardite-Na
occurs on joint surfaces and in cavities in chlorite
schist and
amphibolite
(IZA).
At the type locality for ferrierite-Mg, Kamloops Lake, Kamloops Mining Division, British Columbia, Canada,
abundant ferrierite-Mg occurs in cavities of altered flow breccias
of olivine basalt. Associated
minerals include
chalcedony, quartz,
calcite, and rarely
clinoptilolite-Na.
Other occurrences in British Columbia are in at Monte Lake and in altered
basalt at
Pinaus Lake, both in the Kamloops District
(IZA).
At Honcova hurka near Pribor, northern Moravia, Czech Republic, ferrierite occurs in hydrothermal veins cutting
picrite, associated with with
harmotome,
heulandite, chlorite and carbonates
(IZA).
At Albero Bassi, Vicenza, Italy ferrierite-Mg occurs in calcite filled
veins cutting deeply weathered porphyritic volcanic rock
(IZA).
Ferrierite from Albero Bassi - Image
In the Sangjeongdong district, Yeongil area, Korea, rhyolitic
tuffaceous rocks probably deposited in a lacustrine setting are variably
replaced with
ferrierite in association with mordenite
(IZA).
In the Green Tuff region of Japan, where ferrierite occurs it is associated with
mordenite in the
clinoptilolite-mordenite
metamorphic zone, with a lower limit of about 50oC and an upper limit
of about 90oC
(IZA).
At Tadami-machi, Fukushima Prefecture, Japan, ferrierite with
clinoptilolite and
mordenite comprises up to 40% of the altered
tuff
beds
(IZA).
At Monbetsu, Hokkaido, Japan, ferrierite occurs in veins cutting thick sections of weakly altered
basalt and andesite
(IZA).
In northern Honshu, Japan, ferrierite is a rare mineral occurring sporadically in veinlets within the
mordenite zone, which is the outermost of several hydrothermal zones. These
zones are thought
to have formed after the ores were deposited and covered with sediment. The capping sediment allowed cooling hydrothermal
waters to spread outward, becoming alkaline and allowing zeolite crystallisation.
The temperature
of ferrierite formation is probably consistent with that of the
mordenite-clinoptilolite
zone of diagenesis, less than 150o°C
(IZA).
At Silver Mountain, Alpine County, California, USA, ferrierite occurs in veins cutting thick sections of weakly
altered
basalt and andesite
(IZA).
Ferrierite-K occurs in several localities in the vicinity of Agoura, Santa Monica Mountains, Los Angeles County,
California, USA,
one of which is the type locality. The host rock is porphyritic andesite
breccia with a glassy groundmass. Associated minerals include
clinoptilolite-Na, chalcedony
and
opal
(IZA).
In northwest Nevada, USA, there are two occurrences of diagenetic ferrierite in
rhyolitic pyroclastic sediment, that are at least in part lacustrine.
They are in the Trinity Range northwest of Lovelock, Pershing County and in the Stillwater Range near Fallon, Churchill
county. At the Lovelock occurrence
thick ferrierite beds are overlain by increasingly higher contents of
mordenite
(IZA).
At the type locality for ferrierite-Na is the Altoona-Pillar Rock Road roadcuts, Altoona, Wahkiakum county,
Washington, USA,
ferrierite-Na occurs with mordenite and
clinoptilolite in vesicles of glassy, tholeiitic
basalt
(IZA).
Ferrierite-(Na) from the Altoona-Pillar Rock
Road roadcuts - Image
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