Amesite

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Amesite
Amesite-190280.jpg
General
Category Phyllosilicates
Kaolinite-serpentine group
Formula
(repeating unit)		Mg2Al2SiO5(OH)4
IMA symbol Ame [1]
Strunz classification 9.ED.15
Crystal system Triclinic
Crystal class Pedial (1)
(same H-M symbol)
Space group C1
Unit cell a = 5.307(1), b = 9.195(2)
c = 14.068(3) [Å]
α = 90.09(2)°
β = 90.25(2)°, γ = 89.96(2)°; Z = 4
Identification
ColorWhite, colorless, pink to lilac, pale green
Crystal habit Crystals form as platy to tapering elongated pseudohexagonal prisms
Twinning Common as six-fold sector twins on {001} and polysynthetic twins parallel to {010}
Cleavage Perfect on {001}
Tenacity Brittle
Mohs scale hardness2.5–3
Luster Pearly
Streak White with pale green tint
Diaphaneity Transparent to translucent
Specific gravity 2.77
Optical propertiesBiaxial (+)
Refractive index nα = 1.597 nβ = 1.599 nγ = 1.615
Birefringence δ = 0.018
Other characteristicsKaolinite-serpentine group
References [2] [3] [4]

Amesite is a mineral with general formula of Mg2Al2SiO5(OH)4. [3]

Amesite crystallizes in the triclinic crystal system. [5] It contains three axes of unequal length, not at right angles.

It was first described in 1876 for an occurrence in the Chester Emery Mines, Chester, Hampden County, Massachusetts. It was named for mine owner James Ames. [4] [3] It occurs in an environment of low-grade metamorphism affecting rocks with high aluminium and magnesium content. It occurs associated with vesuvianite, chlorite, magnetite, rutile, diaspore, grossular, calcite, diopside and clinozoisite in various locations. [2]

Amesite is an uncommon silicate mineral which has been reported from a variety of locations worldwide. [3] Amesite has the first reported natural occurrence of the 6R polytype for a trioctahedral 1:1 layer silicate. [6]

Related Research Articles

<span class="mw-page-title-main">Sillimanite</span> Nesosilicate mineral

Sillimanite or fibrolite is an aluminosilicate mineral with the chemical formula Al2SiO5. Sillimanite is named after the American chemist Benjamin Silliman (1779–1864). It was first described in 1824 for an occurrence in Chester, Connecticut.

<span class="mw-page-title-main">Uvarovite</span> Chromium-bearing garnet group

Uvarovite is a chromium-bearing garnet group species with the formula: Ca3Cr2(SiO4)3. It was discovered in 1832 by Germain Henri Hess who named it after Count Sergei Uvarov (1765–1855), a Russian statesman and amateur mineral collector. It is classified in the ugrandite group alongside the other calcium-bearing garnets andradite and grossular.

<span class="mw-page-title-main">Tremolite</span> Amphibole, double chain inosilicate mineral

Tremolite is a member of the amphibole group of silicate minerals with composition Ca2(Mg5.0-4.5Fe2+0.0-0.5)Si8O22(OH)2. Tremolite forms by metamorphism of sediments rich in dolomite and quartz, and occurs in two distinct forms, crystals and fibers. Tremolite forms a series with actinolite and ferro-actinolite. Pure magnesium tremolite is creamy white, but the color grades to dark green with increasing iron content. It has a hardness on Mohs scale of 5 to 6. Nephrite, one of the two minerals known as the gemstone jade, is a green crystalline variety of tremolite.

<span class="mw-page-title-main">Willemite</span> Nesosilicate mineral

Willemite is a zinc silicate mineral and a minor ore of zinc. It is highly fluorescent (green) under shortwave ultraviolet light. It occurs in a variety of colors in daylight, in fibrous masses and apple-green gemmy masses. Troostite is a variant in which part of the zinc is partly replaced by manganese, it occurs in solid brown masses.

<span class="mw-page-title-main">Oldhamite</span> Rocksalt group, sulfide mineral

Oldhamite is a calcium magnesium sulfide mineral with the chemical formula (Ca,Mg)S. Ferrous iron may also be present in the mineral resulting in the chemical formula (Ca,Mg,Fe)S. It is a pale to dark brown accessory mineral in meteorites. It crystallizes in the cubic crystal system, but typically occurs as anhedral grains between other minerals.

<span class="mw-page-title-main">Afghanite</span> Tectosilicate mineral

Afghanite, (Na,K)22Ca10[Si24Al24O96](SO4)6Cl6, is a hydrous sodium, calcium, potassium, sulfate, chloride, carbonate alumino-silicate mineral. Afghanite is a feldspathoid of the cancrinite group and typically occurs with sodalite group minerals. It forms blue to colorless, typically massive crystals in the trigonal crystal system. The lowering of the symmetry from typical (for cancrinite group) hexagonal one is due to ordering of Si and Al. It has a Mohs hardness of 5.5 to 6 and a specific gravity of 2.55 to 2.65. It has refractive index values of nω = 1.523 and nε = 1.529. It has one direction of perfect cleavage and exhibits conchoidal fracture. It fluoresces a bright orange.

<span class="mw-page-title-main">Afwillite</span> Nesosilicate alteration mineral also sometimes found in hydrated cement paste

Afwillite is a calcium hydroxide nesosilicate mineral with formula Ca3(SiO3OH)2·2H2O. It occurs as glassy, colorless to white prismatic monoclinic crystals. Its Mohs scale hardness is between 3 and 4. It occurs as an alteration mineral in contact metamorphism of limestone. It occurs in association with apophyllite, natrolite, thaumasite, merwinite, spurrite, gehlenite, ettringite, portlandite, hillebrandite, foshagite, brucite and calcite.

<span class="mw-page-title-main">Fraipontite</span> Zinc aluminium silicate mineral

Fraipontite is a zinc aluminium silicate mineral with a formula of (Zn,Al)3(Si,Al)2O5(OH)4.

<span class="mw-page-title-main">Eucryptite</span>

Eucryptite is a lithium bearing aluminium silicate mineral with formula LiAlSiO4. It crystallizes in the trigonal – rhombohedral crystal system. It typically occurs as granular to massive in form and may pseudomorphically replace spodumene. It has a brittle to conchoidal fracture and indistinct cleavage. It is transparent to translucent and varies from colorless to white to brown. It has a Mohs hardness of 6.5 and a specific gravity of 2.67. Optically it is uniaxial positive with refractive index values of nω = 1.570 – 1.573 and nε = 1.583 – 1.587.

<span class="mw-page-title-main">Kegelite</span> Silicate mineral

Kegelite is a complex silicate mineral with formula Pb8Al4Si8O20(SO4)2(CO3)4(OH)8.

<span class="mw-page-title-main">Iranite</span> Triclinic lead copper chromate silicate mineral

Iranite (Persian: ایرانیت) is a triclinic lead copper chromate silicate mineral with formula Pb10Cu(CrO4)6(SiO4)2(F,OH)2. It was first described from an occurrence in Iran. It is the copper analogue of hemihedrite (Pb10Zn(CrO4)6(SiO4)2(F,OH)2).

<span class="mw-page-title-main">Ashburtonite</span> Rare lead copper silicate-bicarbonate mineral

Ashburtonite is a rare lead copper silicate-bicarbonate mineral with formula: HPb4Cu2+4Si4O12(HCO3)4(OH)4Cl.

<span class="mw-page-title-main">Stillwellite-(Ce)</span> Rare-earth boro-silicate mineral

Stillwellite-(Ce) is a rare-earth boro-silicate mineral with chemical formula (Ce,La,Ca)BSiO5.

<span class="mw-page-title-main">Boltwoodite</span> Hydrated potassium uranyl silicate mineral

Boltwoodite is a hydrated uranyl silicate mineral with formula (K0.56Na0.42)[(UO2)(SiO3OH)]·1.5(H2O), distinct in crystal structure from sodium boltwoodite, which has an orthorhombic structure rather than monoclinic. It is formed from the oxidation and alteration of primary uranium ores. It takes the form of a crust on some sandstones that bear uranium. These crusts tend to be yellowish with a silky or vitreous luster.

<span class="mw-page-title-main">Cymrite</span> Phyllosilicate mineral

Cymrite is a silicate mineral with the chemical formula BaAl2Si2(O,OH)8·H2O. The mineral is named for Cymru, which is the Welsh word for Wales.

<span class="mw-page-title-main">Gilalite</span>

Gilalite is a copper silicate mineral with chemical composition of Cu5Si6O17·7(H2O).

Larnite is a calcium silicate mineral with the formula Ca2SiO4. It is the calcium member of the olivine group of minerals.

<span class="mw-page-title-main">Sonolite</span>

Sonolite is a mineral with formula Mn9(SiO4)4(OH,F)2. The mineral was discovered in 1960 in the Sono mine in Kyoto Prefecture, Japan. In 1963, it was identified as a new mineral and named after the Sono mine.

<span class="mw-page-title-main">Minnesotaite</span> Iron silicate mineral

Minnesotaite is an iron silicate mineral with formula: (Fe2+,Mg)3Si4O10(OH)2. It crystallizes in the triclinic crystal system and occurs as fine needles and platelets with other silicates. It is isostructural with the pyrophyllite-talc mineral group.

<span class="mw-page-title-main">Hemihedrite</span> Rare lead zinc chromate silicate mineral

Hemihedrite is a rare lead zinc chromate silicate mineral with formula Pb10Zn(CrO4)6(SiO4)2(F,OH)2. It forms a series with the copper analogue iranite.

References

  1. ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID   235729616.
  2. 1 2 Handbook of Mineralogy
  3. 1 2 3 4 Mindat.org
  4. 1 2 Webmineral data
  5. ↑ Roberts, W.L. (1974) Encyclopedia of Minerals, p. 18. Van Nostrand Reinhold Company, New York, New York.
  6. ↑ Hall, Stephen H; Bailey, S.W. (5 January 1976). "Amesite From Antartica" (PDF). American Mineralogist . 61: 497–499. Retrieved 28 October 2022.


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