Hematite
The oligistic hematite , or , is a Minéral composed of Oxide iron of formula FeO. It is the polymorphic α; of FeO, polymorphic the γ; being the Maghémite.
It is a mineral very running, of black color with silver plated, brown gray with red, or red. If it is reduced powders some, hematite, whatever its variety, gives red glares.
The name of hematite is borrowed from Latin hematites , to him even borrowed Greek αίματίητς , derived from αίμα which means “blood”. The hematite powder was used besides as red pigment.
Crystalline structure
Hematite has a noted structure D5 in Notation Strukturbericht. It is a rhomboedric structure, of group of space (n°167). A reason is composed of two reversed FeO pentahedrons which are repeated with the nodes of the rhombohedron. Its cell parameters sont :- has = 5,43 Å ;
- α = 55,26° = 55°16'.
The ions O 2 form a network compact Hexagonal, with thus an alternation of A-B plans; ; the ions Fe 3+ the two-thirds of the octahedral sites intersitiels occupy, with three types of plans has, B and C in alternation. There is thus a A-a-b-B-c-a-A-b-c-B-a-b-A-c-a-B-b-c-A-a alternation… Cell parameters in this hexagonal description sont :
- has = 5,04 Å ;
- C = 13,78 Å.
| Random links: | Grosrouvre | Roullet-Saint-Estèphe | Miguel Bump | Arsita | Intrepid (Star Trek) | T-80 |