Ferrierite comprises three 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
They are tectosilicate (framework silicates), 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+

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, hypersthene, augite, montmorillonite, chalcedony and calcite (HOM).


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 is 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).

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).

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