Amesite

General
Category| Phyllosilicate minerals
Formula
(repeating unit)| Mg2Al2SiO5(OH)4
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
Color| White, 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 hardness| 2.5–3
|re|er}}| Pearly
Streak| White with pale green tint
Diaphaneity| Transparent to translucent
Specific gravity| 2.77
Optical properties| Biaxial (+)
Refractive index| nα = 1.597 nβ = 1.599 nγ = 1.615
Birefringence| δ = 0.018
Other characteristics| Kaolinite-serpentine group
References| [1][2][3]

Amesite is a mineral with general formula of Mg2Al2SiO5(OH)4.[2]

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.[3][2] 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.[1]

Amesite is an uncommon silicate mineral which has been reported from a variety of locations worldwide.[2] Amesite has the first reported natural occurrence of the 6R polytype for a trioctahedral 1:1 layer silicate.[6]

## References

1. ↑ 1.0 1.1 Handbook of Mineralogy
2. ↑ 2.0 2.1 2.2 2.3 Mindat.org
3. ↑ 3.0 3.1 Webmineral data
4. ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine 85 (3): 291–320. doi:10.1180/mgm.2021.43. Bibcode: 2021MinM...85..291W.
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" (in en-US). American Mineralogist 61: 497–499. http://www.minsocam.org/ammin/AM61/AM61_497.pdf. Retrieved 28 October 2022.

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Phyllosilicates

Micas|

* Aluminoceladonite
* Anandite
* Annite
* Aspidolite
* Balestraite
* Bityite
* Biotite
* Boromuscovite
* Bramallite
* Celadonite
* Chernykhite
* Chromphyllite
* Clintonite
* Eastonite
* Ephesite
* Ferroaluminoceladonite
* Ferroceladonite
* Fluorannite
* Fluorokinoshitalite
* Fluorophlogopite
* Fluorotetraferriphlogopite
* Garmite
* Glauconite
* Gorbunovite
* Hendricksite
* Illite
* Kinoshitalite
* Lepidolite
* Luanshiweiite
* Manganiceladonite
* Margarite
* Masutomilite
* Montdorite
* Muscovite
* Nanpingite
* Norrishite
* Orlovite
* Oxyphlogopite
* Paragonite
* Phlogopite
* Polylithionite
* Preiswerkite
* Roscoelite
* Siderophyllite
* Suhailite
* Tainiolite
* Tetraferriannite
* Trilithionite
* Voloshinite
* Wonesite
* Yangzhumingite

Talcs|

* Minnesotaite
* Talc
* Willemseite

Pyrophyllite series|

* Ferripyrophyllite
* Pyrophyllite

Kaolinites|

* Bismutoferrite
* Dickite
* Halloysite
* Hisingerite
* Kaolinite
* Nacrite

Serpentines|

* Amesite
* Antigorite
* Berthierine
* Brindleyite
* Caryopilite
* Chrysotile
* Cronstedtite
* Fraipontite
* Greenalite
* Guidottiite
* Kellyite
* Lizardite
* Manandonite
* Népouite
* Odinite
* Pecoraite

Corrensites|

* Aliettite
* Brinrobertsite
* Corrensite
* Dozyite
* Hydrobiotite
* Karpinskite
* Kulkeite
* Lunijianlaite
* Rectorite
* Saliotite
* Tosudite

Smectites and vermiculite family|

* Beidellite
* Ferrosaponite
* Montmorillonite
* Nontronite
* Saponite
* Sauconite
* Swinefordite
* Vermiculite
* Volkonskoite
* Yakhontovite

Chlorites|

* Baileychlore
* Borocookeite
* Chamosite
* Clinochlore
* Cookeite
* Donbassite
* Gonyerite
* Nimite
* Pennantite
* Sudoite

Allophanes|

* Allophane
* Chrysocolla
* Imogolite
* Neotocite

Sepiolites|

* Falcondoite
* Ferrisepiolite
* Sepiolite

Pyrosmalites|

* Friedelite
* Mcgillite
* Nelenite
* Pyrosmalite
* Schallerite

Stilpnomelanes|

* Bannisterite
* Franklinphilite
* Lennilenapeite
* Parsettensite
* Stilpnomelane

Structural groups mainly; based on rruff.info/ima, modified

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