Porcelain Clay
Porcelain is white, hard, and non-absorbent, unlike so-called "earthen" ceramics.
The raw material for porcelain is a stone called potter's stone. The stone is broken into small pieces to remove impurities such as iron, and then water is added to make the clay (porcelain clay) used to produce porcelain.
Since the discovery of potter's stone at Izumiyama in Arita Town in 1616, the stone has been mined to such an extent that almost all of its mountain has disappeared, and the sight of its magnet site is a magnificent reminder of its 400-year history.
Since the Taisho era (1912-1926), the percentage of pottery stone produced in Amakusa, Kumamoto Prefecture, accounts for about 99% of the raw materials used in the production of Arita-ware. It is said that only Senzan and Amakusa potter's stones can produce porcelain from a single potter's stone without mixing other clay or raw materials, and they are regarded as high-quality and valuable magnets that are unprecedented in the world.
陶土
磁器はいわゆる“土もの”の陶器と違って白く、堅く、吸収性がありません。
磁器の原料は陶石と呼ばれる石です。陶石を細かく砕いて鉄分等の不純物を除去し、水を含ませ磁器生産用の粘土（磁器土）を作ります。
1616年に有田町の泉山で陶石が発見されて以降はその一山のほとんどが姿を消すほどに採掘され、その磁石場の光景は400年の壮大な歴史を感じるものになっています。
大正以降の現在においては、有田焼の生産原料には熊本県天草産の陶石の使用率が約99%を占めています。また、他の土や原料を配合せずに単独の陶石だけで磁器が造れるのは泉山陶石と天草陶石のみと云われ、世界的にも例を見ない高品質で貴重な磁石と評価されています。
※ Senzan Pottery Stone (泉山陶石)