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other names: Sodium borate, Tinkal
mineral class: Borates
chemical formula: N / A2B4O5(OH)4 · 8 (H2O)
Chemical elements: Sodium, boron, oxygen, hydrogen
Similar minerals: Soda, Sassolin
colour: white, green, yellow
shine: Matt to glossy
crystal structure: monoclinic
mass density: 1,7
magnetism: not magnetic
Mohs hardness: 2,5
stroke color: White
transparency: transparent to opaque
use: because of toxicity the use is forbidden
borax or sodium borate describes a mineral which belongs to the group of borates and which appears in differently shaped crystals or mineral aggregates and has a mussel-like breakage and a matt to glassy gloss. The name of the mineral derives from "bauraq", the Arabic name for "white" and refers to its mostly colorless, light gray or whitish, more rarely greenish or bluish appearance, which can be both transparent and opaque. Borax was first described in Europe in 1748 by the researcher Johan Gottschalk Wallerius in Sweden, after the mineral was first discovered in India in 1546 and later on named in Agricola's work "De re metallica".
As a sedimentary mineral borax arises after dehydration and evaporation of saline waters. These waters are also known as Borax lakes and are especially widespread in Death Valley. Borax consists of a boron atom core and sodium and water of crystallization molecules and is therefore classified as sodium salt. Borax is now classified as a hazardous substance as it restricts fertility and is suspected of causing fructification. Therefore, borax-based chemicals are banned today in many countries worldwide.
Occurrence and localities:
Worldwide there are about sixty known sites in the form of desiccated salt lakes, which are mainly confined to South America, the United States, Tibet and China, India, Turkey and some European countries. The most significant mining area is California, particularly the salt lakes of the Death Valley and some borax mines in today's ghost towns, where over half of the world's borax is mined. At the same time, borax crystals are also found in thermal springs and as mineral efflorescence on volcanic soils, where they are often associated with evaporite minerals such as gypsum, calcite, Kornit or Ulexit.
History and usage:
Borax has historically been used in the manufacture of many different products due to its diverse properties as a reactive, soft and light mineral that dissolves in both water and glycerin. Already the ancient Egyptians used it to embalm corpses. Borax was previously used in the production of enamelware and for the production of glazes for ceramics, porcelain, clay or glass. Today it is mainly used in industry to extract boric acid. Borax is also suitable as a cleaning and disinfecting agent, insecticide and herbicide and as an effective anti-mildew agent. However, as it is suspected of causing harm to unborn children, products containing borax are no longer allowed to be sold to households in many countries. In Asia, borax is still used as a food additive that can change the consistency of food. In most European countries, the addition of borax to foods other than real caviar is banned because of its harmful effects.