MATERIALS WHICH PROMOTE VISUAL TEXTURE, TRANSPARENCY,
OPACITY AND DURABILITY 


I. Visual texture 

1. LIO, lithium - mottled effects and strong flow patterns.
.1 - .7%
2. TI, titanium - mottled effects, streaking, speckles and
crystals. .5 - 12% 
3. PO, phosphorus - strong characteristically mottled
effects and glaze flow. .5 - 2% 
4. ZRO, zirconium - small pattern of light and dark
speckles.  8 - 14% 
5. CAO, calcium - at cone 8 or above only - strongly mottled
effects. 10 - 30% 


II. Transparency

1. SIO, silica. 60 - 70%
2. KNAO, sodium and potassium.  6 - 12%
3. BO, boron,  5 - 30%
4. TI, titanium,  5 - 2%
5. ZN, zinc.  .5 - 4%


III. Opacity

1. SN, tin.        0.5 - 4%
2. TI, titanium.   6 - 16%
3. ZN, zinc.      12 - 16%
4. ZR, zirconium.  8 - 14%


IV. Matness

1. AL alumina, 12 - 40%
2. CA calcium (below cone eight) 8 - 30% 
3. TI titanium, 8 - 16% 
4. ZN Zinc,  8 - 20% 


V.  Durability

1. SI, silica 40 - 70%
2. AL, alumina, 12 - 20%
3. TI, titanium. .5 - 8%
4. ZN, zinc .5 - 8%