Baricite
| Baricite | |
|---|---|
 ( total sample size : 7.1 cm × 6.6 cm × 2.3 cm) |
|
| General and classification | |
| other names |
IMA 1975-027 |
| chemical formula | Mg 3 [PO 4 ] 2 • 8H 2 O |
|
Mineral class (and possibly department) |
Phosphates, arsenates, vanadates |
|
System no. to Strunz and to Dana |
8.CE.40 ( 8th edition : VII / C.13) 03/40/06/02 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | C 2 / m (No. 12) |
| Lattice parameters |
a = 10.08 Å ; b = 13.42 Å; c = 4.67 Å β = 104.9 ° |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 1.5 to 2 |
| Density (g / cm 3 ) | measured: 2.35 to 2.42; calculated: 2.448 |
| Cleavage | completely after {010} |
| colour | colorless to light blue |
| Line color | white to light blue |
| transparency | translucent |
| shine | Glass gloss, pearlescent |
| Crystal optics | |
| Refractive indices |
n α = 1.547 to 1.554 n β = 1.553 to 1.564 n γ = 1.582 to 1.595 |
| Birefringence | δ = 0.035 to 0.041 |
| Optical character | biaxial positive |
| Axis angle | 2V = 55 to 60 ° (measured); 60 to 62 ° (calculated) |
| Pleochroism | visible: X = blue; Y, Z = colorless |
Baricite , sometimes misspelled baricite or baricite, is a very rarely occurring mineral from the mineral class of " phosphates , arsenates and vanadates " with the chemical composition Mg 3 [PO 4 ] 2 · 8H 2 O. It is therefore chemically one hydrous magnesium phosphate.
Baricite crystallizes in the monoclinic crystal system and develops predominantly tabular, b-axis stretched crystals up to twelve centimeters long and five centimeters thick with a glass-like sheen on the surfaces. In its pure form it is colorless and transparent. However, due to multiple refraction due to lattice construction defects or polycrystalline design, it can also appear white and take on a light blue color due to foreign admixtures, whereby the transparency decreases accordingly.
With a Mohs hardness of 1.5 to 2, baricite is one of the soft minerals that can be scratched with the fingernail , similar to the reference mineral gypsum (2). Baricite is flexible in thin layers and flakes, but it can also be split very easily along the b-axis , which is already indicated by the often-found, scale-like aggregate forms . The cleavage surfaces have a pearlescent sheen.
Etymology and history
Barićit was named after the former head of the Mineralogical Museum and professor of mineralogy at the University of Zagreb Ljudevit Barić (1902-1984).
Barićit was first discovered at Rapid Creek and Big Fish River in the Dawson mining area in the Canadian Yukon Territory . The mineral was scientifically described in 1976 by Bozidar Darko Sturman and Joseph Anthony Mandarino .
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the baricite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "water-containing phosphates without foreign anions ", where it belongs together with Annabergit , Arupit , Bobierrit , Cattiit , Erythrin , Hörnesit , Köttigit , Manganohörnesit , Pakhomovskyit , Parasymplesit and Vivianit the "Vivianit-Gruppe" with the system no. VII / C.13 formed.
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), assigns baricite to the class of “phosphates, arsenates and vanadates” and there to the category of “phosphates, etc., without additional anions; with H 2 O “. However, this section is further subdivided according to the relative size of the cations involved and the molar ratio of phosphate, arsenate or vanadate complex (RO 4 ) to crystal water (H 2 O), so that the mineral can be classified in the sub-section " With only medium-sized cations; RO 4 : H 2 O ≤ 1 "is found, where it together with Annabergit, Arupit, Erythrin, 2.5 Ferrisymplesit , Hörnesit, Köttigit, Manganohörnesit, Pakhomovskyit, Parasymplesit, Santabarbarait and Vivianit the" Vivianit group "with the System no. 8.CE.40 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking area , assigns the baricite to the class of "phosphates, arsenates and vanadates" and there in the department of "water-containing phosphates etc.". Here, too, he is together with Annabergit, Arupit, Erythrin, Hörnesit, Köttigit, Pakhomovskyit, Parasymplesit and Vivianit in the "Vivianite group" with the system no. 40.03.06 within the subsection " Water-containing phosphates etc., with (A 2+ ) 3 (XO 4 ) 2 × x (H 2 O) ".
Crystal structure
Baricite crystallizes monoclinically in the space group C 2 / m (space group no. 12) with the lattice parameters a = 10.08 Å ; b = 13.42 Å; c = 4.67 Å and β = 104.9 ° and 2 formula units per unit cell .
Education and Locations
At its type locality in the area around Rapid Creek and Big Fish River in Yukon, Canada, Barićite is found as fracture fillings in the sidereal iron formations there, where it occurs in paragenesis with siderite , vivianite, lazulite , whiteit , collinsite , childrenite and quartz .
The only other known discovery site so far (as of 2012) is near Marlborough in the northeast of the South Island of New Zealand, where the mineral was found folded into ribbon-like mass in the sediment of a raised beach.
See also
literature
- BD Sturman, JA Mandarino: Barićite, the magnesium analogue of vivianite, from Yukon Territory, Canada , in: The Canadian Mineralogist , Volume 14 (1976), pp. 403–406 ( PDF 310.6 kB )
- Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1979, ISBN 3-342-00288-3 , p. 626 (as Baričite ) .
Web links
Individual evidence
- ↑ a b c d e Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 481 .
- ↑ Webmineral - Barićite
- ↑ a b c d John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Barićite , in: Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 52.7 kB )
- ↑ a b c d e f Mindat - Barićite