Granito caolinizado

El Cornwall Stone es usado en cerámica como fuente de óxidos fundentes en la pasta y esmaltes. Se asemeja al feldespato. Dado que puede sufrir metamorfismo, en realidad hay diversas clases en cuanto a composición dependiendo del grado de alteración. Los azules y púrpuras (menos alterados) contiene más K₂O y Na₂O, y flúor que los blancos.

Conocido de diversas formas como China stone, Cornwall stone, Cornish stone, Pegmatita, Graven. Gowen, Manx stone, Meldon stone, Growan, Petunste, Amakusa,

Tony Hansen

Tony, propone para el cálculo del sustituto realizar una media de las distintas composiciones existente en la bibliografía.

Receta para sustituir Cornwall stone.

Feldespato Custer..... 15.00

Nefelina sienita... 22.00

Caolín.............. 6.00

Sílice.............. 20.50

Talco................ 1.50

-------

65.00

Ron Roy

Ron's Seger molecular unity formula for Cornwall Stone based on H&G's analysis.

CORN STN............ 100.00

FORMULA & ANALYSIS

• CaO........ .26 2.02%
• MgO........
• K2O........ .29 3.74%
• Na2O....... .44 3.74%
• Fe2O3...... .01 .14%
• TIO2....... .01 .07%
• AL2O3...... 1.16 16.14%
• SiO2....... 9.03 73.65%
• P2O5....... .03 .51%

• RATIO 7.76
• EXPAN 399.42
• WEIGHT 735.81

Ron's calculated sub (untested) for his Cornwall Stone (untested) based on the unity formula - note higher expansion than the original.

• G 200 SPAR.......... 59.00
• EPK................. 12.50
• SILICA.............. 26.00
• WHITING............. 2.50

• FORMULA & ANALYSIS

• CaO........ .26 1.93%
• MgO........ .00 .02%
• K2O........ .52 6.54%
• Na2O....... .22 1.84%
• Fe2O3...... .01 .16%
• TIO2....... .00 .04%
• AL2O3...... 1.17 16.07%
• SiO2........... 9.12 73.39
• P2O5....... .00 .02%
• RATIO 7.77
• EXPAN 424.57
• WEIGHT 746.03

Rons duplication based on the calculated percent of oxides in the fired material. Note the calculated expansion in this last one compares better with the H&G analysis but there is a greater difference in the oxides present when you look at the unity formula - can someone explain the difference to me?

I do know there are some people in industry that use the fired % analysis instead of the molecular formula for problem solving - anyone have a clue as to why?

• G 200 SPAR.......... 53.00
• EPK................. 15.50
• SILICA.............. 28.50
• WHITING............. 3.00

---

100.00

• FORMULA & ANALYSIS

• CaO........ .30 2.18%
• MgO........ .01 .03%
• K2O........ .49 5.94%
• Na2O....... .21 1.66%
• Fe2O3...... .01 .18%
• TIO2....... .00 .05%
• AL2O3...... 1.23 16.20%
• SiO2....... 9.50 73.74%
• P2O5....... .00 .02%

• RATIO 7.74
• EXPAN 398.48
• WEIGHT 772.69

GlazeChem

Fuente:

For: 1.00 Cornwall Stone Sub:

• 0.65 Custer feldspar (27)
• 0.04 Whiting
• 0.13 Kaolin
• 0.22 Silica

For: 1.00 Cornwall Stone Sub:

• 0.65 Custer feldspar (28)
• 0.04 Whiting
• 0.11 Calcined kaolin
• 0.22 Silica

For: 1.00 Cornwall Stone Sub:

• 0.63 Custer feldspar (29)
• 0.04 Whiting
• 0.05 Alumina
• 0.30 Silica

For: 1.00 Cornwall Stone Sub:

• 0.61 Custer feldspar (30)
• 0.04 Whiting
• 0.09 Alumina hydrate
• 0.30 Silica

For: 1.00 Cornwall Stone Sub:

• 0.48 Nepheline syenite (31)
• 0.04 Whiting
• 0.12 Kaolin
• 0.38 Silica

For: 1.00 Cornwall Stone Sub:

• 0.49 Nepheline syenite (32)
• 0.05 Whiting
• 0.10 Calcined kaolin
• 0.38 Silica

For: 1.00 Cornwall Stone Sub:

• 0.48 Nepheline syenite (33)
• 0.05 Whiting
• 0.05 Alumina
• 0.44 Silica

For: 1.00 Cornwall Stone Sub:

• 0.48 Nepheline syenite (34)
• 0.04 Whiting
• 0.07 Alumina hydrate
• 0.44 Silica

For: 1.00 Cornwall Stone Sub:

• 0.67 Kona F-4 (35)
• 0.02 Whiting
• 0.07 Kaolin
• 0.25 Silica

For: 1.00 Cornwall Stone Sub:

0.66 Kona F-4 (36)

• 0.02 Whiting
• 0.06 Calcined kaolin
• 0.26 Silica

For: 1.00 Cornwall Stone Sub:

• 0.66 Kona F-4 (37)
• 0.02 Whiting
• 0.03 Alumina
• 0.29 Silica

For: 1.00 Cornwall Stone Sub:

• 0.65 Kona F-4 (38)
• 0.02 Whiting
• 0.04 Alumina hydrate
• 0.29 Silica

For: 1.00 Cornwall Stone Sub:

• 0.67 G-200 feldspar
• 0.04 Whiting
• 0.09 Kaolin
• 0.25 Silica

For: 1.00 Cornwall Stone Sub:

• 0.67 G-200 feldspar (40)
• 0.03 Whiting
• 0.08 Calcined kaolin
• 0.25 Silica

For: 1.00 Cornwall Stone Sub:

• 0.66 G-200 feldspar (41)
• 0.03 Whiting
• 0.04 Alumina
• 0.29 Silica

For: 1.00 Cornwall Stone Sub:

• 0.67 G-200 feldspar (42)
• 0.03 Whiting
• 0.05 Alumina
• 0.29 Silica