From Digital Fire (links will take you to the digital fire pages also):

This feldspar is being imported by Laguna Clay into North America (from India). It will be marketed as the successor to G-200 feldspar and its temporary substitute, the MFEL S3470 blend (Minspar/G-200HP blend). The chemistry of this is very similar to G-200 (this has a little more K₂O, a little less Al₂O₃and a little more SiO₂).

The manufacturers data sheet describes it as a selected white firing high grade potassium feldspar typically used in frits, ceramic glazes, sanitary ware, table ware, white glass, TV tubes etc. The data sheet calls it PF-01 Potassium Feldspar so there is some confusion about what it will be called.

The analysis supplied here has been rationalized from that supplied on the manfacturers data sheet. It specifies plus or minus values for oxides as follows:
SiO₂ +/- 1%
Al₂O₃ +/- 0.5%
K₂O +/- 1%
Na₂O +/- 0.5%
CaO < 0.3%
Fe₂O₃ +/- 0.02%
MgO < 0.3%
TiO2 < 0.01%
LOI 1% max

Mineralogy: 65-75% Microcline
21-30% Albite
0.6% Anorthite
1% Kaolinite
10-15% Quartz

Melting temperature: 1220C (soaking time 30 minutes)
Particle size: 2% +63 microns (the data sheet lists others but this is the one being imported by Laguna Clay)