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Soda Feldspar
Na2O.Al2O3.6SiO2
Chemistry
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Links to Other Materials
- Nepheline Syenite - Unspecified
- Cache
Miscellaneous
- Family: Feldspar
- Region: North America
- Mined At: Unspecified
- Raw Mineral: No
- Generic: Yes
Notes
Soda Feldspar is generally a clean white mineral which sources sodium, alumina and silica along with some potassium and calcium. Albite mineral from which soda feldspar is derived is often tends to be white in appearance compared with the pinkish hue of orthoclase mineral from which potash feldspar is ground. It begins melting around 800C.
In many cases soda and potash feldspar are interchangeable in glaze recipes. However, some differences will be apparent. For example, slightly different color responses will be encountered (i.e. cobalt tends toward purple copper toward blue with soda spar). Sometimes colors will be brighter with soda feldspar. In addition, soda spar has a higher coefficient of expansion and melts earlier and has a shorter range before it begins to volatilize.
Because sodium has the highest expansion of all oxides and because soda feldspar is high in this oxide, glazes with a lot of soda spar tend to craze. Thus, if any glaze recipe has more than 30% soda feldspar, it is wise to test carefully to assure the glaze is not in tension.
Data
- Melting Point (MP): 1170-1200C
- Specific Gravity: 2.60
- Hardness (Moh): 6-7
- Melting Point (MP): 1170-1200C
Suppliers
- Generic
Authors
- Tony Hansen (Owner)
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