Ardaite

Ardaite (IMA symbol: Ada[1]) s a very rare sulfosalt mineral with chemical formula Pb₁₉Sb₁₃S₃₅Cl₇ in the monoclinic crystal system,[2][3] named after the Arda river, which passes through the type locality.[4] It was discovered in 1978 and approved by the International Mineralogical Association in 1980.[5][6][7] It was the second well-defined natural chlorosulfosalt, after dadsonite.[8]

Ardaite
Ardaite associated with galenite, Madjarovo polymetallic ore deposit, National Natural History Museum, Sofia, Bulgaria
General
Category	Sulfosalt minerals, Lead minerals
Formula (repeating unit)	Pb19Sb13S35Cl7
Strunz classification	2.LB.30 (10 ed) 2/E.19-20 (8 ed)
Dana classification	02.15.01.01
Crystal system	Monoclinic Unknown space group
Identification
Color	Greenish gray or bluish green
Mohs scale hardness	2.5-3
Luster	Metallic
Density	6.44
Pleochroism	Weak
References	Breskovska, V. V.; Mozgova, N. N.; Bortnikov, N. S.; Gorshkov, A. I.; Tzepin, A. I. (1982), "Ardaite, a new lead-antimony chlorsulphosalt" (PDF), Mineral. Mag., 46: 357–361

Greenish gray or bluish green in color, its luster is metallic. Ardaite occurs as 50 µm fine-grained aggregates of acicular crystals associated with galena, pyrostilpnite, anglesite, nadorite, and Cl-bearing robinsonite and semseyite, in the Madjarovo polymetallic ore deposit in Bulgaria. Ardaite has a hardness of 2.5 to 3 on Mohs scale and a density of approximately 6.44.[2]

The type locality is the Madjarovo polymetallic ore deposit in the Rhodope mountains.[9][10] Later its occurrence was proved in the Gruvåsen deposit, near Filipstad, Bergslagen, Sweden.[6]