Ilmenite

Ilmenite
Introduction:
Ilmenite is a weakly magnetic titanium-iron oxide mineral which is iron-black or steel-grey. It is a crystalline iron titanium oxide (FeTiO3). It crystallizes in the trigonal system, and it has the same crystal structure as corundum and hematite. Ilmenite is commonly recognised in altered igneous rocks by the presence of a white alteration product, the pseudo-mineral leucoxene. Often ilmenites are rimmed with leucoxene, which allows ilmenite to be distinguished from magnetite and other iron-titanium oxides. In reflected light it may be distinguished from magnetite by more pronounced reflection pleochroism and a brown-pink tinge. Ilmenite is weakly magnetic, with a weak response to a hand magnet.

Chemical composition and its chemistry:
Ilmenite most often contains appreciable quantities of magnesium and manganese and the full chemical formula can be expressed as (Fe,Mg,Mn,Ti)O3. Ilmenite forms a solid solution with geikielite (MgTiO3) and pyrophanite (MnTiO3) which are magnesian and manganiferous. The vast bulk of ilmenites are restricted to close to the ideal FeTiO3 composition, with minor mole percentages of Mn and Mg. At higher temperatures it has been demonstrated there is a complete solid solution between ilmenite and hematite. Altered ilmenite forms the mineral leucoxene, an important source of titanium in heavy mineral sands ore deposits. Most ilmenite is mined for titanium dioxide production. Finely ground titanium dioxide is a bright white powder widely used as a base pigment in paint, paper and plastics.

The Physical Characteristics Of Ilmenite
· Colour is black.
· Luster is metallic, submetallic to dull when tarnished.
· Transparency: Crystals are opaque.
· Crystal System: Trigonal; bar 3
· Crystal Habits include thin and thick tabular crystals with rhombohedral truncations (similar to hematite's tabular habits); sometimes formed into rosettes. Also granular and massive. Occurs as grains in placer sands.
· Cleavage is absent.
· Fracture is conchoidal or uneven.
· Hardness is 5 - 6
· Specific Gravity is 4.5 - 5.0 (average for metallic minerals).
· Streak is brownish black.
· Other Characteristics: Sometimes magnetic (will always become magnetic if heated) and there is basal and rhombohedral parting.

Associated minerals:
Associated Minerals include zircon, hematite, magnetite, rutile, spinel, analcime, albite, apatite, monazite, calcite, natrolite, microcline, olivine, pyrrhotite, biotite nepheline and quartz.

World resources:
North America and Europe together consume about 50% of the world's titanium dioxide production. Demand by India and China is growing rapidly and may eventually surpass Western consumption. World consumption rises approximately 5% to 8% per annum, with demand growth most strongly centred in Asian economies. World demand in 2004 was 335,000 tonnes of TiO2 units, representing about 2.4 million tonnes of ilmenite. Australia was the world's largest producer and exporter of ilmenite ore in 2005-2006, with 1.1 million tonnes, followed by South Africa (952Kt), Canada (809Kt), China (~400Kt) and Norway (380Kt). Development of large mineral sands operations in Sénégal, Côte d'Ivoire, Madagascar[5] and Mozambique will see extensive supplies of ilmenite, rutile, zircon and leucoxene reach world markets in coming years. This is reflected in the table at right in parentheses. This additional supply of ilmenite and titanium feedstock, approximating 1.5 million tonnes per annum, is in excess to world demand growth of 350Kt per annum.

Question and answers:
1. What is Ilmenite?
A. Ilmenite is a weakly magnetic titanium-iron oxide mineral which is iron-black or steel-grey. It is a crystalline iron titanium oxide (FeTiO3).

2. What is the crystal structure of Ilmenite?
A. It crystallizes in the trigonal system, and it has the same crystal structure as corundum and hematite.

3. What are the properties of ilmentie?
A. Its colour is black, luster is metallic, subm
etallic to dull when tarnished,
Specific Gravity is 4.5 - 5.0,
hardness is 5 – 6.  
 

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