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Formula: Al2SiO3(OH)4
Phyllosilicate (sheet silicate),
allophane group
Crystal System: Monoclinic
Specific gravity: 2.70 measured and calculated
Hardness: 2 to 3
Streak: White
Colour: Yellowish white, light brownish yellow, blue, green, brown
Environments:
Imogolite occurs principally in soils derived from volcanic ash. It has been found associated with
allophane,
halloysite,
vermiculite,
goethite,
gibbsite, cristobalite,
limonite and
quartz. Imogolite has been observed in cracks in
weathered plagioclase
(Dana, HOM).
Imogolite consists of a network of nanotubes with an outer diameter of ~2 nm and an inner diameter of ~1 nm.
The tube walls are formed by continuous Al(OH)3 (gibbsite) sheets
and orthosilicate anions (O3SiOH groups). Owing to its tubular structure, natural availability, and low
toxicity, imogolite has potential applications in polymer composites, fuel gas storage, absorbents, and as a
catalyst support in chemical catalysis
(Wiki).
Localities
At the type locality, Uemura, Kumamoto, Japan, imogolite occurs as a decomposition product of volcanic ash in
soils in a humid environment
(Mindat).
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