Images
Formula: Ni2+4.5(AsO4)3
Arsenate of nickel,
paramorph of
johanngeorgenstadtite
Crystal System: Tetragonal
Specific gravity: 5.222 calculated for the empirical formula, 5.245 calculated for the ideal formula
Hardness: 4
Streak: Pale pink
Colour: Violet-red to red-orange
Luminescence: No fluorescence was observed under long wave or short wave UV
Solubility: At room temperature, insoluble in concentrated hydrochloric acid and in concentrated sulphuric acid
Environments
Niasite is a relatively new mineral, approved in 2019 and to date (October 2024) reported only from the
type locality.
Localities
At the type locality, Johanngeorgenstadt, Erzgebirgskreis, Saxony, Germany, niasite and
johanngeorgenstadtite are associated with
aerugite, bunsenite,
quartz, rooseveltite and
xanthiosite. The assemblage is apparently
secondary in origin and most likely formed from the breakdown of
primary nickeline
under dry (low relative humidity) and oxidising conditions.
Niasite occurs in sugary aggregates of violet-red to red-orange irregular, rounded grains or short prisms that
are about 50 µm in diameter. No forms could be determined and no twinning was observed. The streak is pale pink.
Crystals are transparent with resinous to subadamantine lustre, brittle with conchoidal fracture and no cleavage
(EJM 32.3.373-385).
Niasite from Johanngeorgenstadt -
Image
Back to Minerals