Titanium-bearing minerals

Aluminum is the third most abundant (7.5%) chemical element in the earth s crust. Aluminosilicate clay deposits are plentiful throughout the world. However, the extraction of aluminum from these deposits is not economically feasible. The principal aluminum ore in the world is bauxite, which usually represents a collection of different minerals such as gibbsite, diaspore, and boehmite. Also, other iron- and titanium-bearing minerals are many times found in bauxite. 

It is interesting that yellow zircon luminescence is very specific and different from other Zr-bearing minerals such as catapleite, keldyshite, vlasovite, khibinskite and others, which are usually characterized by blue luminescence evidently connected with titanium impurity, namely TiOe complexes (Gaft et al. 1981). 

Rutile is formed primarily by the crystallization of magma with high titanium and low iron contents, or by the metamorphosis of titanium-bearing sediments or mag-matites. The rutile concentrations in primary rocks are not workable. Therefore, only sands in which rutile is accompanied by zircon and/or ilmenite and other heavy minerals can be regarded as reserves. The world reserves of rutile are estimated to... 

In an extensive review of the geochemistry of volatile-bearing minerals in mantle xenoliths, Ionov et al (1997) have pointed out that although minerals such as mica, amphibole, and apatite are often referred to as hydrous, in many cases they have very low H2O contents (Boettcher and O Neill, 1980). In such cases, these minerals may have significant amounts of fluorine, chlorine and CO2. Mica, amphibole, and apatite, together with the oxide phases, are important hosts for titanium, potassium, rubidium, strontium, barium, and niobium (Table 9). 

The actinides (U, Th, Pu), alkaline earths (Be, Mg, Ca, Sr, Ba), lanthanides (elements La - Lu), Al, and the elements in groups 3b (Sc, Y), 4b (Ti, Zr, Hf), and 5b (V, Nb, Ta) of the periodic table are refractory lithophile elements. The refractory lithophiles are 5% of the total mass of the rock in solar composition material. Aluminum Al, calcium Ca, and titanium Ti are the three most abundant refractory lithophiles, and they form minerals that are the host phases for most of the less abundant refractory lithophile elements such as the actinides, lanthanides, and transition elements in group 5b of the periodic table. Some of the less abundant refractory lithophiles - the group 4b elements Zr, Hf, and the group 3b elements Y and Sc - condense as oxides before any Ca, Al, Ti-bearing minerals form [9], But the rest condense into the more abundant host phases. 

Pyrite, and other iron-bearing minerals such as hematite and llmonite, provide the iron that primarily is responsible for the colour of bricks. The presence of other constituents, notably calcium, magnesium or aluminium oxides, tends to reduce the colouring effect of iron oxide, whereas the presence of titanium oxide enhances it. High original carbonate content tends to produce yellow bricks. 

With a relative abundance in the Earth s crust of 122 mg/kg, chromium is the 21st most abundant element and the 6th most abundant transition metal after iron, titanium, manganese, zirconium, and vanadium it is more abundant than nickel, zinc, and copper. Though native chromium is extremely rare (e.g, Udachnaya Mine in Russia), most common chromium-bearing minerals are the spinel-type mineral chromite [FeCr O, cubic] and, to a lesser... 

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