MINOR METALS

Columbite , also called  niobite ,  niobite-tantalite  and  columbate  [( Fe ,  Mn ) Nb 2 O 6 ], is a black  mineral  group that is an ore of  niobium . It has a submetallic  luster  and a high density and is a niobate of  iron  and  manganese .  Detailed description This mineral group was first found in  Haddam, Connecticut , in the United States. It forms a series with the  tantalum -dominant analogue  ferrotantalite  and one with the manganese-dominant analogue  manganocolumbite . The iron-rich member of the columbite group is  ferrocolumbite . Some tin and tungsten may be present in the mineral.  Yttrocolumbite  is the yttrium-rich columbite with the formula (Y,U,Fe)(Nb,Ta)O 4 . It is a radioactive mineral found in  Mozambique . Columbite has the same composition and crystal symmetry ( orthorhombic ) as  tantalite . In fact, the two are often grouped t...

Gallium (pronounced /ˈ ɡ æliəm/ , GAL-ee-əm ) is a chemical element that has the symbol Ga and atomic number 31. Elemental gallium does not occur in nature, but as the gallium(III) salt in trace amounts in bauxite and zinc ores. A soft silvery metallic poor metal , elemental gallium is a brittle solid at low temperatures. As it liquefies slightly above room temperature , it will melt in the hand. Its melting point is used as a temperature reference point, and from its discovery in 1875 to the semiconductor era, its primary uses were in high-temperature thermometric applications and in preparation of metal alloys with unusual properties of stability, or ease of melting; some being liquid at room temperature or below. The alloy Galinstan (68.5% Ga, 21.5% In, 10% Sn) has a melting point of about −19 ° C (−2.2 ° F ). Detailed description In semiconductors , the major-use compound is gallium arsenide used in microwave circuitry and infrared applications. Gallium nitride and ...

Germanium (pronounced /dʒərˈme ɪ niəm/ , jər-MAY-nee-əm ) is a chemical element with the symbol Ge and atomic number 32. It is a lustrous, hard, grayish-white metalloid in the carbon group , chemically similar to its group neighbors tin and silicon . Germanium has five naturally occurring isotopes ranging in atomic mass number from 70 to 76. It forms a large number of organometallic compounds, including tetraethylgermane and isobutylgermane Detailed description Germanium was discovered comparatively late because very few minerals contain it in high concentration. Germanium ranks near fiftieth in relative abundance of the elements in the Earth's crust . In 1869, Dmitri Mendeleev predicted its existence and some of its properties based on its position on his periodic table and called the element eka-silicon . Nearly two decades later, in 1886, Clemens Winkler found it in the mineral argyrodite . Winkler found that experimental observations agreed with Mendeleev...