Eudialyte

The mineral is a rarely occurring Eudialyt ring silicate having the chemical composition Na15Ca6Fe3Zr3Si ( Si25O73 ) ( O, OH, H 2 O ) 3 ( Cl, OH ) 2 It crystallizes in the trigonal crystal system and developed prismatic to tabular crystals, but also grained mineral aggregates in pink and red to brown in color.

Special Features

Eudialyt distinguished in that it can be extremely easily liquefy. Before the blowpipe it melts very quickly to a pale green colored glass bead, without color the flame. Furthermore, the mineral is also very sensitive to acids. Even doused with cold acids Eudialyt discolored very quickly and easily and completely gelatinized in it. Also by annealing this property is not lost, it requires to complete gelation, however, the involvement of a weak digestive heat (about body warm between 28 ° to 30 or max. ° 40 ).

Eudialyte is slightly radioactive with a specific activity of about 158.2 Bq / g (compared to natural potassium 31.2 Bq / g).

Etymology and history

The name eudialyte is composed of the Greek words εὖ [ EU] " well, proficient " or as a prefix εὐ - [ eu ] "good " ( related to the Mycenaean eu-/eu̯- prefix /, the ancient Indian prefix su - [ vasu or "good" ] and the Hittite assu - adjective for each "good ", originally from * ἐσύ [ ESU ] or * h1sú ) and διάλυτος, which in turn is composed of διά " by, for, apart " (possibly related to [ δίς ] " twice "or δύω [ dúɔ ː ] " two " ) and λύω [ lúɔ ː ] " solve " ( etymology unclear ).

Eudialyte was first described in 1819 by Friedrich Stromeyer, who, after his special property of being easily fusible and soluble in acid, named the mineral. As a type locality applies the Illimaussaq complex in Kitaa (Greenland)

Classification

In the old ( 8th edition ) and new classification of minerals according to Strunz ( 9th edition ) of the eudialyte is part of the Department of ring silicates ( cyclo- silicates). The new Strunz'sche Mineral classification divided here but now more specific to the type and size of the merged into rings SiO4 tetrahedra. Thus Eudialyt belongs according to its formula for division of the ring silicates with "[ Si9O27 ] 18 - Nine -rings ".

The classification of minerals according to Dana assigns the eudialyte also the Ringsilicaten to, here, however, the subdivision " rings with other anions and insular silicate groups with mixed ring types." He, together with 18 other minerals named after him Eudialytgruppe.

Modifications and varieties

  • Eukolit, Eucolit or Barsanovit also contains cerium and lanthanum and is a softer variety of Eudialyts with an altered appearance.

Education and Locations

Eudialyt forms in igneous rocks such as nepheline syenite pegmatite or. There in paragenesis with aegirine, nepheline and / or microcline occurs.

So far, the mineral at 139 sites open (as of 2009), as including in New South Wales, Queensland and Tasmania (Australia ); the north and south to south-eastern regions of Brazil; Liaoning (China ); except in its type locality Kitaa still in tunu to Greenland; Los Iceland in Guinea (Africa ); British Columbia, Quebec ( Mont St. Hilaire ), Newfoundland and Labrador ( Canada); Antsiranana in Madagascar; Langesundsfjord in Norway; several regions in Russia ( Kukisvumchorr, Khibinymassiv, Kola ); Bohemia in the Czech Republic; as well as some regions of the United States.

Crystal structure

Eudialyte crystallized in the trigonal crystal system in the space group with the lattice parameters a = 14.2646 Å and c = 30.186 Å and 12 formula units per unit cell.

Use as a gemstone

Eudialyt place due to its vivid coloring in conjunction with other minerals, for example, in the rock syenite occasionally used as a gemstone. He usually comes in the form of drum stones or Cabochonen, but also facets sections were already applied. Ring silicates | cyclosilicate

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