Botryogen

Botryogen is a hydrous magnesium sulfate mineral with formula: MgFe³⁺(SO₄)₂(OH)·7H₂O. It is also known as quetenite.^[3]

Botryogen
Specimen from Mina Santa Elena, Alcaparrosa, San Juan, Argentina with a red colored crystal of botryogen in a matrix of butlerite, copiapite and parabutlerite (size:5.7 x 4.1 x 2.5 cm)
General
Category	Sulfate minerals
Formula	MgFe3+(SO4)2(OH)·7H2O
IMA symbol	Byg[1]
Strunz classification	7.DC.25
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P21/n
Identification
Mohs scale hardness	2 - 2.5
Specific gravity	2.14
References	[2]

It crystallizes in the monoclinic prismatic system and typically occurs as vitreous bright yellow to red botryoidal to reniform masses and radiating crystal prisms. It has a specific gravity in the range 2 to 2.1 and Mohs hardness in the range of 2 to 2.5.^[4]

It occurs in arid climates as a secondary alteration product of pyrite-bearing deposits.^[5]

It was first described in 1828 for an occurrence in the Falu mine of Falun, Dalarna, Sweden. It was named for its grape like appearance from Greek botrys for "bunch of grapes" and genos meaning "to bear".^[4]