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Arsenic Oxide

Alternate Names: Arsenious oxide, Arsenic trioxide

Oxide Analysis Formula
As2O3 100.00% 1.00
Oxide Weight 198.00
Formula Weight 198.00


A white poisonous powder derived from the roasting of arsenopyrite (mispickel). It is available in dense large crystal form and a glassy form (made by heating under pressure).

The material can be used as a reagent in glass batches. Lumps thrown into the tank sink, vaporize, and rise sweeping away fine bubbles.

Because of its oxidizing effect, it can be used as a fining agent to clarify iron containing glass. It will also fade the color of manganese and stabilize other colors (i.e. light green). In pot glasses large quantities are used to reduce yellow coloration. Arsenic oxide is also used in specialized enamels (i.e. jewelry).

A major problem with the material is toxicity due to its vaporization on melting. This limits its use to tightly controlled environments.

Related Information


Hazards Arsenic Oxide
Oxides As2O3 - Arsenic Oxide
Arsenic trioxide on Wikipedia
Typecodes Flux Source
Materials that source Na2O, K2O, Li2O, CaO, MgO and other fluxes but are not feldspars or frits. Remember that materials can be flux sources but also perform many other roles. For example, talc is a flux in high temperature glazes, but a matting agent in low temperatures ones. It can also be a flux, a filler and an expansion increaser in bodies.


Glaze OpacifierIt can be used as an opacifier in glazes, although not as effective as tin. It creates a fine matrix of bubbles that impede light passage.
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