[1] Keisha

Keisha is sand made of "quartz" that contains a substance called silicon dioxide. Keisha is also found in sand in park sandboxes, and if you look closely at the sand, you can find transparent, sparkling keisha. When making glass, quartz and other ores called "silica stone" are ground into small pieces.

Quartz itself is colorless, but impurities may mix with it to give it color. For example, "rose quartz" is colored like a rose, "agate" is made of several impurities that have been neatly layered over hundreds or thousands of years, and "quartz" is made of quartz crystals that have grown so large that they resemble hexagonal pillars. Quartz crystals are sometimes crushed and used as raw materials for glass.

［2] Soda ash

As the word "ash" suggests, it was originally made from the ashes of burned plants and trees, but nowadays, anhydrous sodium carbonate made from salt is ^used2). In addition to glass, it is also used as an ingredient in soap, detergents, and bath salts, and is also found in "brine," which softens Chinese ^noodles3).

［3] Limestone

This mineral is also used in chalk, and is extracted from limestone, which is mainly composed of a calcium carbonate-containing mineral called ^calcite4). Limestone is distributed throughout Japan and is extracted from more than 200 mines. Akiyoshidai in Yamaguchi Prefecture, Hiraodai in Fukuoka Prefecture, and Geibi Gorge in Iwate Prefecture are famous for their limestone-rich terrain.

In addition to soda-lime glass, which is used for windows, bottles, tableware, etc., there are other types of glass, including borosilicate (heat-resistant) glass, which is resistant to heat and chemicals and can be used in microwave ovens, ovens, and science experiments, and crystal glass, which is transparent and sparkling. Boric acid glass contains more silica than soda-lime glass, and also contains boron and boric acid. Crystal glass can contain high levels of lead oxide, potassium oxide, barium oxide, or titanium oxide.

*Related Link "How is glass made?"