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Charoite

Class: Silicates

In potassic feldspar metasomatites at the contact of nepheline and aegirine syenites with limestones (Anthony et al., 2001—2005).
Charoite — specimen 0530
Charoite — specimen 0530, photo © NMNHS

Original description: ‘Чароит’ Рогова, В. П., Рогов, Ю. Г., Дриц, В. А., Кузнецова, Н. Н., [Rogova, V. P., Rogov, Y. G., Drits, V. A., Kuznetsova, N. N.], 1978. Чароит — новый минерал и новый ювелирно-поделочный камень [Charoite — a new mineral, and a new jewelеry stone] — Записки Всесоюзного минералогического общества [Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva] 107 (1): 94—100 [view in ‘Library’].

Type locality: Murun Massif, [Aldan Shield, Republic Sakha, Russia] ([Rogova, Rogov, Drits, Kuznetsova], 1978: 94).

Type material: University of Rome, Rome, Italy, 24352; Fersman Mineralogical Museum, Moscow, Russia (Anthony et al., 2001—2005).

Etymology: for the type locality, near Chara River.

Distribution: In the Murun Massif, Aldan Shield, on the border of Republic Sakha and Irkutskaya Oblast, Russia (Anthony et al., 2001—2005).

Chemistry

(K,Sr,Ba,Mn)15-16(Ca,Na)3232Si70(O,OH)180(OH,F)4·nH2O

Essential elements: hydrogen (H), oxygen (O), fluorine (F), sodium (Na), silicon (Si), potassium (K), calcium (Ca), manganese (Mn), strontium (Sr), barium (Ba).

Crystal data

Crystallography: monoclinic — prismatic. Crystal habit: fibrous, massive (Anthony et al., 2001—2005).

Physical properties

Cleavage: good in three directions (Anthony et al., 2001—2005). Fracture: no data. Tenacity: no data. Hardness: 5—6 (Lazzarelli, 2012). Density: 2.54—2.78 g/cm3 (Lazzarelli, 2012). Luminescence: none.

Optical properties

Colour: shades of deep lilac to violet; colourless in thin section (Anthony et al., 2001—2005). Diaphaneity: semitransparent (Anthony et al., 2001—2005). Lustre: vitreous, silky. Refractive index: 1.550—1.559 — anisotropic [biaxial (+)] (Anthony et al., 2001—2005). Birefringence: 0.009. Dispersion: strong. Pleochroism: X = rose; Z = colourless, in thick fragments (Anthony et al., 2001—2005).

Material from ‘Repository’

1 specimen: 0530 — 2.01 ct, Russia, Far Eastern District, Sakha Republic, Aldan Shield, Murunskii Massif.


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