Keilite

Keilite is an iron-magnesium sulfide mineral with the chemical formula (Fe,Mg)S) that is found in enstatite chondrites.^[2] Keilite is the iron-dominant analog of niningerite.^[3][4] Keilite is named after Klaus Keil (born 1934).^[3]

Keilite
General
Category	Sulfides
Formula	(Fe2+,Mg)S
IMA symbol	Ke[1]
Strunz classification	2/C.15-15
Dana classification	2.8.1.9
Crystal system	Isometric
Crystal class	Hexoctahedral
Space group	Fm3m (No. 225)
Unit cell	a = 5.1717(18)Å
Identification
Formula mass	81.91 gm
Colour	Grey
Crystal habit	Microscopic crystals
Cleavage	Distinct/good
Tenacity	Brittle
Luster	Metallic
Diaphaneity	Opaque
Specific gravity	3.958
Density	3.958

Occurrences

Examples of keilite occurrences are enstatite chondrites and the Zakłodzie meteorite.^[4] It appears to be confined to impact-melt influenced enstatite chondrites that were quenched. There are also some meteorites interpreted as impact-melt breccias that do not contain keilite. This is explained as a deeper burial after impact, which slowed cooling and enabled retrograde reactions (diapthoresis) to take place.^[5]