Images
Formula: [Mg2(K,Na)2Ca0.5](Si29Al7)O72.18H2O
Tectosilicate (framework silicate), ferrierite subgroup,
zeolite group, formerly called "ferrierite", renamed in 1997
Crystal System: Orthorhombic
Specific gravity: 2.136 measured, 2.11 calculated
Hardness: 3 to 3½
Streak: White
Colour: White, colourless, pinkish, orange to red
Environments
Volcanic igneous environments
Metamorphic environments
Ferrierite-Mg occurs as an alteration product of basalts and as
a diagenetic material in rhyolitic
tuffaceous sediments and in metamorphic rocks
(Webmin).
Ferrierite is a high-silica zeolite commonly found in a silica-rich
environment. The presence of ferrierite in sedimentary (diagenetic) deposits indicates it can crystallise at
low temperatures.
Mineral association is an important aid to the recognition of ferrierite. It is commonly found with the
high-silica minerals heulandite,
dachiardite,
mordenite,
quartz and chalcedony. It is
not found with the low-silica zeolites,
levyne, cowlesite,
thomsonite, mesolite,
natrolite, scolecite,
gismondine and
garronite
(ZW).
Localities
At the Wollongong Council Quarry, Unanderra, Camden County, New South Wales, Australia, colourless, freestanding,
2.5-mm, radial groups of closely packed, bladed, Mg-rich ferrierite (ie ferrierite-Mg) co-crystallised with
transparent heulandite crystals in large vesicles in
trachyandesite. One large pocket showed the sequence:
laumontite → coarse brown
calcite → fine-grained light-blue
chalcedony-calcite →
ferrierite → calcite →
heulandite → bladed
calcite → aragonite prisms,
while other parts of the rock contained pyrite,
mordenite and quartz
(ZW).
Ferrierite-Mg from the Wollongong Council
Quarry - Image
At Phillip Island, Bass Coast Shire, Victoria, Australia, free-growing, small, radiating, needlelike tufts of
Mg-rich ferrierite (ie ferrierite-Mg), up to 2 mm across, composed of flat blades, coloured white to salmon,
commonly appearing green from numerous clay inclusions are found in
weathered vesicular basalt near Pyramid Rock, on the southern coast
of the Island. The ferrierite is associated with water-clear, blocky
heulandite and black
clay, while nearby cavities are filled with
calcite. Ferrierite is also found on Phillip Island, in an area
from Red Cliff Head to Berry's Beach. The ferrierite specimens are composed of fibrous snow-white, pink,
greenish, or bluish crusts, and globular coatings consisting of thin plates several millimeters long that are
commonly associated with chabazite,
heulandite, baryte,
calcite and
montmorillonite in vesicular
basalt at Red Cliff Head
(ZW).
Ferrierite-Mg from Phillip Island -
Image
At the Basalt quarry, Weitendorf, Wildon, Leibnitz District, Styria, Austria, Mg-rich ferrierite
(ie ferrierite-Mg) has been reported in cavities in columnar K-rich
basalt (= shoshonite)
of a volcanic cone. Small needles in
basalt have been known at this locality since 1909, but were thought
to be natrolite. The ferrierite forms attractive white, yellow or
grey needles not over 0.01 mm across and 2 mm long that form radiating hemispheres or cavity linings associated with
small, colourless, blocky, silica-rich heulandite,
harmotome, clay,
aragonite, and chalcedony.
The crystals are needlelike, rather than forming blades
(ZW).
Ferrierite-Mg from Weitendorf -
Image
At the S6 motorway tunnel, Tanzenberg, Kapfenberg, Bruck-Mürzzuschlag District, Styria, Austria, tiny, radiating
aggregates of ferrierite, composed of thin blades with feathered irregular terminations, are found on joints
and cavities of chlorite
schists and
amphibolites. The ferrierite is associated with
Na-rich dachiardite (ie dachiadrite-Na) crystals, silica-rich
heulandite, analcime,
mordenite, octahedral and filiform (thread-like)
pyrite, marcasite,
quartz, siderite,
sphalerite, chalcopyrite,
pyrrhotite, millerite,
opal, rutile,
anatase, goethite,
dolomite, calcite,
magnesite, ankerite and
baryte
(ZW).
At Lieschengraben, Oberhaag, Leibnitz District, Styria, Austria, ferrierite is very rare in fractures
crossing schists and
gneiss in the Diabas Quarry. Nearby veins contain
mordenite, dolomite,
calcite, baryte,
millerite, sphalerite,
chalcopyrite, pyrite and
marcasite
(ZW).
At Zvezdel, Momchilgrad Municipality, Kardzhali Province, Bulgaria, Mg-rich ferrierite (ie ferrierite-Mg)
crystallised in the order: silica-rich heulandite and
ferrierite →
opal-cristobalite and
chalcedony →
dachiardite and
mordenite, in veins that cement
brecciated andesite
(ZW).
At the type locality, Kamloops Lake, Kamloops Mining Division, British Columbia, Canada, the railway cut on the
north shore the lake is the best and most prolific locality in the world for ferrierite. Mg-rich ferrierite
(ie ferrierite-Mg)is abundant in weathered olivine
basalt pillows and
flow-breccia.
Calcite-chalcedony-filled
nodules, lined with small, red, radiating groups of ferrierite on their surface (terminations pointing
inward), commonly reach 8 cm across, with a few reaching 25 cm across. Ferrierite commonly lines the walls
of veins, up to 10 cm thick and 4 meters long, that are filled with an intergrowth of
calcite and chalcedony.
Rarely, geodes, up to 13 cm by 30 cm, are lined with ferrierite, covered by
amethyst or clear quartz crystals,
calcite crystals and small, brown needles of
goethite. The largest ferrierite crystals reach 3 mm wide, 1mm
thick, and up to 15 mm long, forming large, colourless to cloudy cream-colored aggregates, from 2 mm to over 3 mm
across, while smaller crystals are more transparent shades of colourless pink and red. The cavities are coated by a
light green clay that is covered by an egg-shell-thin
chalcedony layer that preceded radial groups and linings of bladed
ferrierite. Rarely, dark red and orange to colourless, blocky, silica-rich
heulandite crystals are present.
Small, colorless to white blades of ferrierite, 1 to 3 mm long, are found on large masses of shiny,
botryoidal marcasite at the Afton Native Copper Mine, across the lake
from the type locality, on the south shore of Kamloops Lake
(ZW).
Ferrierite-Mg from Kamloops Lake -
Image
At Monte Lake, Kamloops Mining Division, British Columbia, Canada, colourless, salmon-orange and red, Mg-rich
ferrierite (ie ferrierite-Mg) is found in calcite-filled vesicles
and veins along the east side of the lake in altered basalt, and in
railway cuts southeast of the lake. The compact blades of ferrierite commonly co-crystallised with
calcite, followed by a colourless generation of ferrierite
covered by more calcite. Large
chalcedony nodules and
quartz geodes are present, yet
chalcedony is rarely found with the ferrierite. Free-growing
ferrierite needles are found in 1 to 8 cm vesicles, with the observed sequence:
siderite →
chalcedony → ferrierite →
clay → calcite. Larger
pockets, up to 15 cm, are found in the Ferrierite Cliffs railway cut southeast of the lake where exceptionally
long, thin, free-growing ferrierite crystals, up to 8 cm long and only 1 mm wide, are present.
basalt flows, above the silica-rich Ferrierite Cliffs, contain an
abundance of stilbite,
apophyllite, mesolite and
chabazite, while red, vesicular flows, at the top of the hill, contain
the low-silica zeolites levyne,
cowlesite, chabazite,
stilbite and thomsonite
(ZW).
Ferrierite-Mg from Monte Lake -
Image
At Pinaus Lake, Westwold, Kamloops Mining Division, British Columbia, Canada, light orange to red blades of Mg-rich
ferrierite (ie ferrierite-Mg) line calcite-filled nodules, up to
4 cm across, in highly altered basalt north of the lake. Less
commonly, ferrierite formed orderly rows of blades crossing each aggregate, and is rarely associated with
heulandite
(ZW).
Ferrierite-Mg from Pinaus Lake -
Image
At Francois Lake, Omineca Mining Division, British Columbia, Canada, some 480 km north of Kamloops Lake, vesicular
andesite contains minute, colourless to white blades of Mg-rich ferrierite
(ie ferrierite-Mg) 2 mm long, that form radial groups with small, brownish
heulandite on massive
collinsite and
carbonate-fluorapatite
(ZW).
Ferrierite-Mg from Francois Lake -
Image
At Karrenberg Quarry, Reichweiler, Kusel-Altenglan, Kusel, Rhineland-Palatinate, Germany, radiating, bladed
aggregates of ferrierite, up to 5 mm across, are found covered by
chalcedony in pyroxene
dacite. Nearby rock contains
natrolite, scolecite,
thomsonite, laumontite,
heulandite, stilbite,
phillipsite, harmotome and
chabazite
(ZW).
At Hungen, Giessen, Giessen Region, Hesse, Germany, ferrierite occurs with
chabazite,
erionite-offretite,
faujasite, levyne,
phillipsite and thomsonite
(ZW).
Mt Oladri Quarries, Monastir, South Sardinia Province, Sardinia, Italy, Mg-rich ferrierite
(ie ferrierite-Mg) is reported in weathered andesite. It
forms free-growing, grey or orange, spherical aggregates of radiating blades, up to 15 mm across, associated with
heulandite and white masses of very thin, hairlike needles of
mordenite. Nearby rock contains
analcime, stilbite,
mesolite and chabazite
(ZW).
Ferrierite-Mg from the Mt Oladri Quarries -
Image
Near the Albero Bassi locality, Santorso, Vicenza Province, Veneto, Italy, a red Mg-rich ferrierite
(ie ferrierite-Mg) is found filling fractures a few millimeters thick, or along the edges of
calcite veins, in a green, weathered
porphyry
(ZW).
Ferrierite-Mg from near Albero Bassi -
Image
At Timonchiello Creek, Schio, Vicenza Province, Veneto, Italy, brownish-red ferrierite blades, 1 mm long,
line cavities filled with calcite
(ZW).
Ferrierite-Mg from the Timonchiello Creek -
Image
At the Tapu ferrierite site, Coromandel Peninsula, Thames-Coromandel District, Waikato Region, New Zealand, a
Ba-Mg-rich ferrierite (ie ferrierite-Mg) forms blades, 1 mm long, lining walls of
calcite-filled veins, up to 3 cm in thickness, crossing
andesite breccia
(ZW).
Lovelock, Antelope Mining District, Pershing County, Nevada, USA. Recent studies have shown that ferrierite
can exhibit a fibrous-asbestiform crystal habit and may possess the same properties as carcinogenic fibrous
erionite. The zeolite-rich
tuff deposit of Lovelock is the largest occurrence of diagenetic
ferrierite-Mg. It has been reported that ferrierite hosted in these rocks displays a fibrous morphology.
Current results prove fibrous ferrierite is widespread and intermixed with
mordenite and orthoclase.
According to the WHO counting criteria, most of the ferrierite fibres can be classified as breathable. However, it
is recommended to adopt a precautionary approach for mining operations in this area to reduce the risk of exposure
(MM 83.4.577–586).
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