Crystallography of jarosite

How is jarosite formed?

Jarosite forms as a secondary mineral in weathered sulfidic ores, coal mine wastes, on oxidizing mine wastes, and in streams affected by acid mine drainage.
Jarosite also forms in acid-sulfate soils, as an alteration product of sulfidic shales, and in hydrothermal environments..

What are the optical properties of jarosite?

Optical Properties: Transparent to translucent.
Color: Amber-yellow to dark brown.
Streak: Pale yellow.
Luster: S뫚mantine to vitreous, resinous on fractures..

What are the physical properties of jarosite mineral?

Jarosite forms as a secondary mineral in weathered sulfidic ores, coal mine wastes, on oxidizing mine wastes, and in streams affected by acid mine drainage.
Jarosite also forms in acid-sulfate soils, as an alteration product of sulfidic shales, and in hydrothermal environments..

What is the composition of jarosite?

It is called sodium jarosite, Fe₆(SO₄)₄(OH)₁₂Na₂.
It contains approximately 50 % Fe, around 30 % SO₃, 6-8 % K₂O and Na₂O and 1.7 % Al₂O₃ (as impurity)..

What is the crystal structure of jarosite?

Jarosite is often produced as a byproduct during the purification and refining of zinc and is also commonly associated with acid mine drainage and acid sulfate soil environments.
Crystals are usually pseudocubic or tabular, also as granular crusts, nodules, fibrous masses or concretionary..

What is the process of jarosite precipitation?

The precipitation of iron as jarosite by hydrolysis generates sulphuric acid and about 40 g/L of H.

1. SO4 must be neutralised in order to achieve near complete iron precipitation.
Three neutralising agents are added; ammonia, calcine and a basic zinc sulphate/gypsum precipitate.