Potassium Alum – Crystal Alum Mineral: A multipurpose mineral for commercial use and collectors.

Potassium alum is the white crystalline natural mineral salt (double sulfate) of potassium.  Potassium alum is specific chemical compound that is also part of a class of alum chemical compounds. The term alum refers to various double sulfates that have the general formula of (SO4)3•24H2O plus an additional element, such as potassium, which results in potassium alum: K2SO4∙Al2(SO4)3∙24H2O. Potassium alum, and alums alike, crystallize in regular octahedral.  It is soluble in water, and when heated it liquefies; and if the heating is continued, an unstructured powder will remain. Commonly, potassium alum crystal is colorless and glassy (vitreous), and in its purest form is completely translucent with small fractures. Potassium alum has been a sought after natural mineral salt for thousands of years due to its abilities to effectively contribute to water purification, pickling, tanning, medical procedures and in cosmetics as an aftershave or deodorant.  Additionally, due to its attractive crystal appearance, potassium alum has become a favorite amongst mineral collectors.  Potassium alum is antimicrobial and can therefore be used as a natural deodorant by inhibiting the growth of the bacteria responsible for body odor. It is also used in medical procedures as a local astringent  and styptic.


Potassium alum (alumbre) is a naturally occurring sulfate mineral which typically occurs as encrustations on rocks in areas of weathering and oxidation of sulfide minerals and potassium-bearing minerals.  The crystal alum mineral is commercially extracted in select quarries throughout the world. It has been reported in Tennessee, and Arizona in the United States, and also, in South America, in the Andies between Bolivia, Chile, Colombia (Azufral), Venezuela (Punta de Araya) and Argentina.

Pricing & Quality

Natural potassium alum pricing varies according to the quality of the mineral crystal or powder.  The overhead and expenses of mining potassium alum, combined with shipping from quarries in remote locations of the world add up; plus, the quality can vary as well.  Basically, the price of potassium alum is directly related to the quality – as the purity of the crystal increases, so does the price.

Natural & Synthetic

Potassium alum is a naturally occurring mineral, but it can also be chemically synthesized with alunite or by mixing aluminum hydroxide with potassium or ammonium sulfate.

potassium alum Natural Potassium Alum Specimen

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