Ilmenite Mineral Overview
- Mineral name: Ilmenite
- Mineral class: Oxide
- Chemical formula: FeTiO₃ (iron titanium oxide)
- Crystal system: Trigonal
- Mohs hardness: 5–6
- Color range: Black, iron-gray
- Luster: Metallic to submetallic
- Streak: Black to brownish-black
- Cleavage: Poor
- Fracture: Uneven to conchoidal
- Specific gravity: Approximately 4.5–5.0
- Transparency: Opaque
- Common locations: Australia, South Africa, Canada, India, Norway
- Uses: Titanium ore, pigments, industrial applications
- Similar minerals: Magnetite, hematite, rutile
Naming and Classification
Ilmenite is an iron titanium oxide mineral, named after the Ilmen Mountains in Russia, where it was first identified.
It is the primary ore of titanium, an element widely used in:
- Aerospace
- Paints and pigments
- Industrial materials
Physical and Optical Characteristics
Ilmenite typically occurs as:
- Massive or granular material
- Disseminated grains in rocks
- Tabular or rhombohedral crystals (less common)
Its color is usually black to iron-gray, often with a slightly:
- Brownish tint
The luster is metallic to submetallic, though it may appear dull in weathered specimens.
With a Mohs hardness of 5–6, it is moderately hard.
Magnetic Properties (Key Feature)
Ilmenite is:
- Weakly magnetic (especially when heated or altered)
It can sometimes be confused with magnetite, but:
- Magnetite is strongly magnetic
- Ilmenite is only weakly or not noticeably magnetic
Chemical Composition and Structure
Ilmenite is composed of:
- Iron (Fe)
- Titanium (Ti)
- Oxygen (O)
It forms part of a solid solution series with:
- Hematite (Fe₂O₃)
This variation can affect:
- Color
- Magnetic properties
Formation and Geological Occurrence
Ilmenite forms in several environments:
Igneous Rocks
- Common in basalt and gabbro
- Forms during crystallization of magma
Placer Deposits
- Concentrated by erosion and water movement
- Found in beach sands (“black sands”)
Metamorphic Rocks
- Present in altered titanium-rich rocks
It is commonly associated with:
- Magnetite
- Rutile
- Garnet
Common Locations
Ilmenite is found worldwide:
- Australia: Major producer (beach sands)
- South Africa: Large deposits
- Canada: Quebec and Ontario
- India and Norway: Important regions
These regions are known for titanium production.
Uses and Practical Significance
Ilmenite is extremely important industrially:
Titanium Production
- Main source of titanium metal
Titanium Dioxide (TiO₂)
- Used in:
- Paints (white pigment)
- Plastics
- Sunscreen
Industrial Applications
- Aerospace alloys
- Corrosion-resistant materials
Similar and Related Minerals
Ilmenite can resemble:
- Magnetite: Strongly magnetic
- Hematite: Red streak instead of black
- Rutile: Different crystal habit and composition
Magnetic behavior and streak help distinguish ilmenite.
Identification Notes for Collectors
- Look for black, heavy mineral
- Note metallic to submetallic luster
- Check streak (black to brownish-black)
- Test weak magnetism
- Consider occurrence in igneous rocks or beach sands
Ilmenite is an iron titanium oxide mineral, recognized for its importance as the primary source of titanium and its widespread occurrence in igneous and placer environments, making it one of the most economically significant oxide minerals.