Zykaite

Zykaite or zýkaite is a grey-white mineral consisting of arsenic, hydrogen, iron, sulfur and oxygen with formula: Fe³⁺₄(AsO₄)₃(SO₄)(OH)·15(H₂O).^[1] This dull mineral is very soft with a Mohs hardness of only 2 and a specific gravity of 2.5. It is translucent and crystallizes in the orthorhombic crystal system.^[2]

Zykaite
Zykaite found in the Czech Republic
General
Category	Minerals
Formula	Fe3+4(AsO4)3(SO4)(OH)·15(H2O)
Identification
Color	Grey-white, Yellow-white, Green-white
Fracture	Irregular, Uneven
Tenacity	Waxy
Mohs scale hardness	2
Luster	Dull
Streak	Pale yellow
Diaphaneity	Translucent
Specific gravity	2.5
Density	2.50 g/cm3

It is in the Sanjuanite-Destinezite mineral group, containing group members Destinezite, Sanjuanite, and Sarmientite.

Its common associates include limonite, gypsum, scorodite, quartz and arsenopyrite.^[2] It is found in the Czech Republic, New Zealand, Poland and Germany.^[3]

Zykaite was first described in 1978 for an occurrence in the Safary mine, Kutná Hora, Bohemia, Czech Republic and named in honour of Vaclav Zyka (born 1926), a Czech geochemist.^[2][3]