Ephesite

A variety of Trioctahedral micas Group

Ephesite specimen - rock identification

What is Ephesite?

Ephesite is a rare member of the mica silicate mineral group, phyllosilicate. It is restricted to quartz-free, alumina rich mineral assemblages and has been found in South African deposits in the Postmasburg district as well as Ephesus, Turkey.

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North ZoneCentral RidgeSouth Basin

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Key Characteristics

Characteristics of Ephesite

Ephesite found in its natural state is translucent and pink in color. It has a vitreous luster and pearly on the cleavages. Categorized as a triclinic crystal system and belongs with the point group 1 symmetry elements, this crystal class includes a one-fold rotation with or without inversion. As a group the micas are characterized by their perfect basal cleavage, giving thin, flexible, and elastic cleavage plates. Crystals are usually tabular with prominent basal planes and hexagonal in outline. Ephesite has been found as 2M1 and 1M polytype series and shows perfect cleavage on the {001} axis.

Composition of Ephesite

Ephesite has an ideal chemical formula of NaLiAl2(Al2Si2)O10(OH)2. Ephesite and paragonite are closely related due to their substitution of sodium in place of potassium. The general form of most micas, which can vary such as in the place of ephesite, can be written as W(X,Y)2-3Z4O10(OH,F)2 as observed by many sources. In the case of ephesite the W compound is sodium and the (X,Y) is lithium and aluminium, it also bears two hydroxides as the end members.

Quick Facts

Physical Properties

Color
Translucent pink
Hardness (Mohs)
3.5 - 4.5

Chemical Properties

Chemical Formula
NaLiAl2(Al2Si2O10)(OH)2
Elements
Al, H, Li, Na, O, Si

Also Known As

EphesiteSoda-margarite
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