Search results
Results From The WOW.Com Content Network
Crystal of potassium alum, KAl(SO 4) 2 ·12H 2 O. An alum (/ ˈ æ l ə m /) is a type of chemical compound, usually a hydrated double sulfate salt of aluminium with the general formula X Al(SO 4) 2 ·12 H 2 O, such that X is a monovalent cation such as potassium or ammonium. [1] By itself, "alum" often refers to potassium alum, with the ...
Crystal structure of alunite. Alunite is an analog of jarosite, where aluminium replaces Fe 3+. Alunite occurs as a secondary mineral on iron sulfate ores. Alunite occurs as veins and replacement masses in trachyte, rhyolite, and similar potassium rich volcanic rocks.
Alum-(K) is a hydrous potassium aluminium sulfate mineral with formula KAl(SO 4) 2 ·12(H 2 O). It is the mineral form of potassium alum and is referred to as potassium alum in older sources. It is a member of the alum group. [2] It occurs as colorless to white, soft isometric crystals and efflorescence coatings. [3]
After the Crusades, alum, an indispensable good in the European fabric industry, [76] was a subject of international commerce; [77] it was imported to Europe from the eastern Mediterranean until the mid-15th century. [78] The nature of alum remained unknown. Around 1530, Swiss physician Paracelsus suggested alum was a salt of an earth of alum. [79]
Aluminium sulfate is sometimes called alum or papermaker's alum in certain industries. However, the name " alum " is more commonly and properly used for any double sulfate salt with the generic formula X Al(SO 4 ) 2 ·12H 2 O , where X is a monovalent cation such as potassium or ammonium .
Ammonium aluminium sulfate, also known as ammonium alum or just alum (though there are many different substances also called "alum"), is a white crystalline double sulfate usually encountered as the dodecahydrate, formula (NH 4)Al(SO 4) 2 ·12H 2 O. It is used in small amounts in a variety of niche applications.
Crystals of alum, the naturally occurring form of which was known back to the ancients. The history of aluminium was shaped by the usage of its compound alum . The first written record of alum was in the 5th century BCE by Greek historian Herodotus . [ 2 ]
Forsterite. In chemistry, isomorphism has meanings both at the level of crystallography and at a molecular level. In crystallography, crystals are isomorphous if they have identical symmetry and if the atomic positions can be described with a set of parameters (unit cell dimensions and fractional coordinates) whose numerical values differ only slightly.