Miargyrite

Miargyrite, formerly known as ruby blende or garnet blende is a mineral, a sulfide of silver and antimony with the formula AgSbS₂. It is a dimorph of cuboargyrite. Originally discovered in the Freiberg district of Germany in 1824, it has subsequently been found in many places where silver is mined. It usually occurs in low temperature hydrothermal deposits. and forms black metallic crystals which may show a dark red internal reflection. The streak is also red.

Miargyrite
Miargyrite, San Genaro Mine, Castrovirreyna District, Peru (size: 6.1 × 4.2 × 2.7 cm).
General
Category	Minerals
Formula	AgSbS2
IMA symbol	May[1]
Strunz classification	2.HA.10
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	C2/c
Identification
Mohs scale hardness	2–2+1⁄2
Streak	red
Specific gravity	5.2
Melting point	514°C
References	[2][3][4]

Miargyrite is named from the Greek meyon, "smaller" and argyros, "silver", as its silver content is lower than most silver sulfides.