Adelite

The rare mineral adelite, is a calcium, magnesium, arsenate with chemical formula CaMgAsO₄OH. It forms a solid solution series with the vanadium-bearing mineral gottlobite. Various transition metals substitute for magnesium and lead replaces calcium leading to a variety of similar minerals in the adelite–duftite group.

Adelite
Pinkish crystal aggregates of adelite from the Franklin deposit in Ogdensburg, New Jersey
General
Category	Adelite-descloizite group
Formula	CaMg(AsO4)(OH)
IMA symbol	Ade[1]
Strunz classification	8.BH.35
Dana classification	41.5.1.1
Crystal system	Orthorhombic
Crystal class	2 2 2 – Disphenoidal
Space group	P212121
Identification
Color	Colourless, white, grey, bluish grey, yellowish grey, yellow, pale green, pinkish brown, brown
Crystal habit	Elongate crystals, massive
Cleavage	None observed
Mohs scale hardness	5
Luster	Vitreous, greasy
Diaphaneity	Transparent, translucent
Specific gravity	3.73 to 3.79
Optical properties	Biaxial (+), colorless (transmitted light)
References	[2]

Adelite forms variably colored (blue, green, yellow and grey) crystals in the orthorhombic crystal system. The form is typically massive. It has a Mohs hardness rating of 5 and a specific gravity of 3.73 to 3.79.

It was first described in 1891 from Värmland, Sweden. Its name comes from the Greek word for indistinct.

Geologic occurrence

Adelite has been found in ore deposits in Algeria, Germany, Italy, Sweden and the US.^[2]

See also

• Descloizite
• List of minerals