Imogolite

Imogolite is an aluminium silicate clay mineral with the chemical formula Al
2SiO
3(OH)
4. It occurs in soils formed from volcanic ash and was first described in 1962 for an occurrence in Uemura, Kumamoto prefecture, Kyushu Region, Japan.[1] Its name originates from the Japanese word imogo, which refers to the brownish yellow soil derived from volcanic ash. It occurs together with allophane, quartz, cristobalite, gibbsite, vermiculite and limonite.[2]

Imogolite
Imogolite soil (brown) with fragments of transparent imogolite films
General
CategoryClay mineral
Formula
(repeating unit)		Al
2SiO
3(OH)
4
Strunz classification9.ED.20
Crystal systemTetragonal
Unknown space group
Identification
ColorWhite, blue, green, brown, black
Crystal habitConchoidal to earthy masses of microscopic threadlike particles and bundles of fine tubes, each about 20 Å in diameter
Mohs scale hardness2–3
LusterVitreous, resinous, waxy
DiaphaneityTransparent to translucent
Specific gravity2.7
Optical propertiesIsotropic
Refractive indexn=1.47–1.51
References[1][2][3]

Imogolite consists of a network of nanotubes with an outer diameter of ca. 2 nm and an inner diameter of ca. 1 nm. The tube walls are formed by continuous Al(OH)
3 (gibbsite) sheets and orthosilicate anions (O
3SiOH 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.[4]

References
  1. "Imogolite: Mineral information, data and localities". Mindat.org. Hudson Institute of Mineralogy. Retrieved 27 Jun 2019.
  2. Anthony JW, Bideaux RA, Bladh KW, et al., eds. (1995). "Imogolite" (PDF). Handbook of Mineralogy. II (Silica, Silicates). Chantilly, VA, US: Mineralogical Society of America. ISBN 9780962209710.
  3. "Imogolite Mineral Data". Webmineral.com. Retrieved 27 Jun 2019.
  4. Yah WO, Yamamoto K, Jiravanichanun N, et al. (2010). "Imogolite Reinforced Nanocomposites: Multifaceted Green Materials". Materials. 3 (3): 1709–1745. doi:10.3390/ma3031709.

Further reading
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