Rutile

[Chemical composition] often contains Fe, Nb, Ta, Cr, Sn and other similar materials. Wherein when referred to as Fe-rich rutile iron, Fe ^2+, and Nb ⁵⁺ (Ta ⁵⁺⁾ and Ti ⁴⁺ to be  aliovalently isomorphous replacement. When Nb is greater than Ta, it is called ruthenium rutile; when Ta is larger than Nb, it is called ruthenium rutile. The composition of rutile can be used as a standard feature: rutile is rich in Nb in alkaline rock; rutile contains V in basic rock and magmatic carbonate; rutile contains Sn in pegmatite; and rutile in moonstone is rich in Nb and Cr.

[Crystal structure] tetragonal system; a ₀ =0.459 nm, c ₀ =0.296 nm; Z=2. The crystal structure of rutile shows that O ^{2 is} approximately hexagonal close-packed, while Ti ⁴⁺ is located in the deformed octahedral void to form Ti-O ₆ octahedral coordination. The Ti ⁴⁺ coordination number is 6, and the O ^2- coordination number is 3. In the crystal structure of rutile, the Ti—O ₆ coordination octahedrons are arranged in a chain along the c-axis. The chains are connected by coordinating octahedral co-angles (Fig. Y-10). The cleavage of the rutile along the c-axis and the cleavage of the parallel extension direction reflect the characteristics of the chain structure.

Figure Y-10 Crystal structure of rutile

(a) an ion-packed form; (b) a crystal structure lattice form and a plurality of unit cell stacks, a chain of [TiO ₆ ] octahedrons joined together in an rib, wherein two [TiO ₆ ] octahedral chains are shown, One is the cell body of Ti as the heart [TiO _6] octahedra chain, another angle cell is centered on top of the Ti [TiO _6] octahedra chain.

[Form] Commonly intact square short column, long column or needle (Figure Y-11), which is related to its formation conditions. When there is a mixture of Nb, Ta, Fe, Sn, etc., it often forms a double-cone, short columnar crystal form, as seen in pegmatite; and when the crystallization rate is fast, a long columnar, needle-like crystal form appears, such as Seen in the rutile quartz vein. Bismuth (101) is an elbow-shaped twin and triplet crystal and a ring-shaped hexagonal crystal; it is rare to form (301) into a heart-shaped twin crystal. The aggregate is in the form of a dense block.

Figure Y-11 Columnar crystal of rutile

[Physical properties] Common brown red, dark red, containing Fe is black; streaks light brown; diamond shiny; slightly transparent. Cleavage parallel {110} medium. Hardness 6 to 6.5. The relative density is 4.2 to 4.3. Crisp. Both iron rutile and coltan rutile are black and opaque. Iron rutile has a relative density of 4.4, while strontium rutile can reach 5.6.

[genesis and occurrence] Rutile is formed in high temperature conditions and is mainly produced in the rutile-bearing quartz veins of the metamorphic rocks and in the pegmatite veins. In addition, it appears as a secondary mineral in igneous rocks and is often found in gneiss in granular form. Rutile is often converted into sand ore after weathering due to its high chemical stability.

[Identification features] Quartet column shape, knee-shaped double crystal, reddish brown, cylindrical cleavage is completely characterized. After cooling, dilute phosphoric acid was dissolved, was added a solution of Na ₂ O can golden brown (reaction of titanium). The difference from similar mineral cassiterite and zircon is: cassiterite has a relatively large relative density (6.8-7.0), while zircon has a relatively large hardness (7.5).

[Main use] is a mineral raw material for titanium smelting. Titanium alloys are widely used in chemical, military and space technologies, such as in jet engines, aircraft bodies and missile rockets; also in reactors, distillation towers, heat exchangers, valves and other equipment and components used in the alkali industry. on. Synthetic rutile can be used to make high-quality welding electrodes; titanium dioxide can be used as a high-grade white oil knee, paint, rayon light-reducing agent, white rubber and high-grade paper filler.