Montmorillonite (English spelling)

Japanese: モンモリロナイト（英語表記）montmorillonite

A type of clay mineral. (Na, Ca) _0.3 (Al, Mg, Fe ³⁺ , Li) _2-3 (Si, Al) ₄ O ₁₀ (OH) ₂・n H ₂ O. The main component mineral of bentonite. Monoclinic crystal system. Specific gravity 2-3, hardness 1-2. White, yellow, green, etc. Three-layer structure with water between the layers, which is dehydrated at 100-200°C. Volcanic rocks and their tuffs, especially natural glass, are prone to weathering and becoming montmorillonite. Plate-like crystals with an unclear shape when viewed under an electron microscope. It has the property of taking in water between the layers and swelling significantly, and has high ion exchange properties. It becomes adhesive at a water content of 150% and loses adhesiveness at a water content of about 450%, and is a clay that exhibits special properties such as low internal friction resistance, and landslides are more likely to occur in areas with a lot of montmorillonite. It is used in mud for drilling oil wells, as a binder for foundry sand molds, and as top dressing for absorbing fertilizer.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

粘土鉱物の一種。 (Na，Ca)_0.3(Al，Mg，Fe³⁺，Li)_2～3(Si，Al)₄O₁₀(OH)₂・nH₂O 。ベントナイトの主成分鉱物。単斜晶系。比重2～3，硬度1～2。白，黄，緑色など。3層構造で層間に水をもち，100～200℃で層間水が脱水する。火山岩やその凝灰岩，特に天然ガラスは風化してモンモリロナイトになりやすい。電子顕微鏡では形のはっきりしない板状の結晶。層間に水を取入れ著しく膨潤する性質があり，イオン交換性が高い。含水量 150%で粘着力を生じ，約 450%の含水量で粘着力を失い，また内部摩擦抵抗が小さいことなど特殊な性質を示す粘土で，地すべりはモンモリロナイトが多いところに起りやすい。石油井を掘進するときに用いる泥水，鋳物砂型の結合剤，肥料分を吸着させるための客土などに用いられる。

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