針ニッケル鉱

針ニッケル鉱 化学特性,用途語,生産方法

• 解説

  針ニッケル鉱，六方晶系，真鍮色の針状結晶の鉱物。放射状に集って産することがある。硬度3～3.5で軟らかく，比重 5.5。金属光沢をもち，条痕は緑黒色。熱水鉱床，塩基性の深成岩に鉱脈として産する。

• 化学的特性

  The mineral millerite is brittle; hardness, 3–3.5; specific gravity, 5.48–5.52; luster, metallic; color, brass-yellow, often with an iridescent tarnish.

• 物理的性質

  Trigonal crystalline solid or amorphous powder; mineral millerite has a yellow metallic luster; color varies from yellow to brownish black; density 5.30 to 6.65 g/cm³; exhibits three allotropic modifications: (1) the acid-soluble amorphous alpha form obtained from nickel salt solution by precipitation with ammonium sulfide, (2) the alpha form rapidly transforms to a crystalline beta form as a brown colloidal dispersion upon exposure to air, and (3) a rhombohedral gamma modification found native as mineral millerite, which also can be prepared artificially under certain conditions.
  Gamma-NiS slowly converts to beta-NiS in solution. Beta form probably is richer in sulfur than alpha and gamma modifications and therefore they could have varying stoichiometric compositions.
  Nickel sulfide melts at 797°C and is insoluble in water (3.6 mg/L at 18°C; soluble in concentrated nitric acid and potassium hydrogen sulfide solution; slightly soluble in alcohol.

• 天然物の起源

  Nickel sulfide occurs in nature as mineral millerite. Its principal use is as a source material for making nickel metal.

• 使用

  MILLERITE is used as an ore of nickel. Millerite was named for the English mineralogist, W.H. Miller.

• 製造方法

  Nickel sulfide is mined directly from natural deposits. Also, it can be prepared in the laboratory by precipitation from an aqueous solution of a nickel salt with ammonium sulfide, (NH₄)₂S, or by precipitation from an acetic acid solution with hydrogen sulfide. While the aqueous solution method yields an amorphous product (alpha-NiS) which rapidly changes on exposure to air and contact with the solution to a brown crystalline sulfide (beta-NiS), the acid solution method forms only crystalline beta-NiS.
  Nickel sulfide also can be prepared by reacting nickel powder with molten sulfur.