Aluminite

Aluminite is a hydrous aluminium sulfate mineral with formula: Al₂SO₄(OH)₄·7(H₂O). It is an earthy white to gray-white monoclinic mineral which almost never exhibits crystal form. It forms botryoidal to mammillary clay-like masses. It is very soft Mohs hardness of 1 with a specific gravity of 1.66—1.7. It forms as an oxidation product of pyrite and marcasite along with aluminous silicates and clays.

Additional recommended knowledge

Don't let static charges disrupt your weighing accuracy

Daily Visual Balance Check

Correct Test Weight Handling Guide: 12 Practical Tips

It was first described in 1807 from Halle, Saxony-Anhalt, Germany. It is also known as alley stone and websterite (named after English geologist Thomas Webster).

Aluminite is used by tile & masonry workers to reduce the setting time of cementitious mortars.

References

• Mindat w/ locations
• Webmineral