STANDING TALL: PLAINS INDIANS ENJOYED HEIGHT, HEALTH ADVANTAGE. COLUMBUS, Ohio - Equestrian Indian tribes on the American Plains in the late 1800s were the tallest people in the world, suggesting that they were surprisingly well-nourished given disease and their lifestyle, a new study found.
Limestone often contains variable amounts of silica in the form of chert (chalcedony, flint, jasper, etc.) or siliceous skeletal fragment (sponge spicules, diatoms, radiolarians), and varying amounts of clay, silt and sand (terrestrial detritus) carried in by rivers.
The major ingredient for glass making is silica, in the form of sand. Only sand of exceptional purity can be used to make glass. If the sand contains a trace of iron, for instance, the glass made with it will have a greenish color. Even for ordinary window glass, sand must be better than 99 percent pure silica, perfectly white, and not too fine. But I guess if you are looking for 4 main ingredients... Silica Sand 60% Soda Ash 20% Limestone 15% Alumina-Silicate 4% Those are the 4 main I could find. But really it's all about the sand.