Quintinite

Quint Init is a very rarely occurring mineral from the mineral class of " carbonates and nitrates " with the chemical composition Mg4Al2 [( OH) 12 | CO3 ] · ​​3H2O, ie it is a hydrous magnesium aluminum carbonate with additional hydroxide ions. Seen crystallographically Quint Init a polytype, ie its crystal structure consists of a layer lattice with alternating crystallizing in hexagonal or trigonal symmetry structural units. To distinguish these are indeed sometimes referred to as Quint Init Init 2H or bottom -3T shall not be considered as independent modifications and minerals.

Quint Init developed thin to dicktafelige or prismatic crystals, but also occurs in the form of pyramidal and rosette -shaped mineral aggregates. In pure form, Quint Init is colorless and transparent. He can also assume a yellow to orange-brown color by foreign admixtures, the transparency decreases accordingly.

Etymology and history

Was first discovered in the bottom Init " Jacupiranga Mine" at Cajati in the Brazilian state of São Paulo ( Quint init 2H) and in the quarry " Poudrette " at Mont Saint- Hilaire in the Canadian province of Québec ( Quint Init - 3T). The mineral was first described in 1997 by George Y. Chao, Robert A. Gault, designated to honor his contributions to the study of the geology of Mont Saint- Hilaire it by Quintin Wight ( b. 1935 ).

The polytypes described by Chao and Gault Quint init 2H and Quint Init -3T in 1992 by the International Mineralogical Association (IMA ) is still recognized as a distinct mineral ( IMA 1992-028 Register-Nr. and IMA 1992-029 ), but lost this status because the 1998 published edition of the IMA guidelines regarding procedures for the recognition of minerals and mineral nomenclature. After this polymorphic forms of a mineral not be regarded as an independent species, if their structures are also topologically different. The structures differ, however, only low due to lattice distortions or by changing or disorder of the stacking sequence of an atomic layer to the next, these polymorphs are not considered independent.

The type material of the mineral is in the Canadian Museum of Nature in Ottawa (catalog Quint init 2H: CMNMI 81546, 47266 CMNMI, CMNMI 81548; Quint Init -3T: CMNMI 81549 ) and the Royal Ontario Museum in Toronto (catalog Quint Init -2H: M46768, M46769, M46770; Quint Init -3T: M46771 ) was preserved.

Classification

In the outdated, but partly still in use 8th edition of the mineral classification by Strunz Quint Init belonged to common mineral class of " carbonates, nitrates and borates " and then to the Department of " water -containing carbonates with foreign anions ", where he along with Barbertonit, Caresit, Charmarit, manasseite, Sjögrenit and Zaccagnait the " manasseite group " with the system no. V/E.02 formed.

The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the bottom Init in the reduced class of " carbonates and nitrates ," there but also in the department of " Carbonates with additional anions, with H2O " one. However, this is further divided according to the relative size of the cations involved, so that the mineral is found according to its composition in the subsection "With medium-sized cations " where there. Than named the " Quint Init group " with the system no Forms 5.DA.40 and the other members Caresit and Charmarit.

The mainly common in English-speaking classification of minerals according to Dana assigns Quint init 2H and Quint Init -3T as the outdated Strunz'sche systematics in the common class of " carbonates, nitrates and borates " and there in the department and the same sub-division of " Carbonate - hydroxyl or halogen, " a. Here he is with Caresit, Charmarit -2H and Charmarit -3T in the " Quint init Charmarit group " with the system no. 16b.06.04 to find.

Education and Locations

Quint Init formed by hydrothermal processes in miarolithischen cavities and pegmatitic rock bodies with nepheline syenites. Accompanying minerals occur among others Caresit and Charmarit.

In addition to its previously described Type localities " Jacupiranga Mine" in Brazil and quarry " Poudrette " at Mont Saint- Hilaire in Canada Quint Init has so far only on the Cerro Sapo in the Bolivian province Ayopaya, in the serpentine - magnesite deposit " Dypingdal " at Snarum ( municipality Modum ) are found in the Norwegian province Buskerud and in the iron mines " Korshunovskoye " at Zheleznogorsk - Ilimski (English Zheleznogorsk ) in the East Siberian County Irkutsk Oblast and " Kowdor Zheleznyi " on the Kola Peninsula in Russia.

Crystal structure

Quint Init -2H hexagonal crystallizes in the space group P6322 ( Raumgruppen-Nr. 182) with the lattice parameters a = 10.57 Å and c = 15.14 Å and four formula units per unit cell.

Quint init 3T trigonal crystallized in the space group P3112 ( Raumgruppen-Nr. 151) or P3212 ( Raumgruppen-Nr. 153) with the lattice parameters a = 10.56 Å and c = 22.71 Å and 6 formula units per unit cell.