Godfrey Spar
A standard material in Glazecalc's library: its oxide analysis, unity contribution and hazards.
What it is
- Kind
- Feldspars and stones
- Status
- Discontinued
- Formula
- CaO: 0.097; K₂O: 0.426; Na₂O: 0.377; Al₂O₃: 0.985; SiO₂: 8.433
- Also called
- Godfrey feldspar, Godfrey
- Sold in
- US
- Similar materials
- Cornish Stone (synthetic substitute) , Nepheline Syenite
- Source
- Glazecalc’s original data (2017), from a ceramics reference book
An old North American potash feldspar, high in silica, found only in US references; a Glazy recipe taken from Grebanier's Chinese Stoneware Glazes calls for 'Godfrey or Maine feldspar'. Listed as no longer available by 1999 (Zamek, Ceramics Monthly). No supplier sells it now.
Oxide analysis and unity formula
Glazecalc has the analysis of Godfrey Spar as moles of each fired oxide per formula. The unity contribution is the moles of each oxide in the amount of Godfrey Spar that holds 1.0 mole of flux, which is how Glazecalc adds it into a recipe's unity formula.
| Oxide | Moles | Unity contribution |
|---|---|---|
| Na₂O | 0.377 | 0.419 |
| K₂O | 0.426 | 0.473 |
| CaO | 0.097 | 0.108 |
| Al₂O₃ | 0.985 | 1.094 |
| SiO₂ | 8.433 | 9.370 |
- Equivalent weight
- 751.16
- Fired weight
- 751.16
- Loss on ignition
- 0%
The equivalent weight is the grams of Godfrey Spar that hold 1.0 mole of flux. The fired weight is what is left of that after firing.
Hazards and safety
Hazards: Fine dust contains respirable crystalline silica; avoid breathing it.
Use it in a recipe
Add Godfrey Spar to a recipe in the Glazecalc calculator to see what it does to a glaze's unity formula.