How to identify Iron Ore

To correctly identify Iron Ore (Iron-rich rock (likely containing hematite, goethite, or limonite)), check each of these features in order. Many rocks and minerals look alike, so cross-reference multiple properties before deciding.

Step-by-step identification

1. 1

   Color

   Overall color and any zoning or banding

   Varies widely: steel-gray to black (magnetite, specular hematite), reddish-brown to red (hematite), yellowish-brown to dark brown (goethite, limonite).

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Metallic to submetallic (hematite, magnetite), dull to earthy (limonite, goethite, some hematite).

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Can be massive, granular, oolitic, pisolitic, banded (BIFs), or earthy. Often dense and heavy.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Individual iron oxide minerals can show distinct crystal forms (e.g., rhombohedral hematite, octahedral magnetite), but in ore bodies, they are often massive or fine-grained aggregates.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Hematite has no true cleavage but exhibits parting. Magnetite has no cleavage. Goethite and limonite typically show no cleavage.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Banded Iron Formations (BIFs) are found in ancient Precambrian shield areas. Other deposits occur in various settings including igneous intrusions, hydrothermal veins, and weathered profiles (laterites).

Key Facts

Hardness

Hematite: 5-6.5; Magnetite: 5.5-6.5; Goethite: 5-5.5; Limonite: 4-5.5 (Mohs scale)

Specific Gravity

Hematite: 4.9-5.3; Magnetite: 5.18; Goethite: 3.3-4.3; Limonite: 2.7-4.3. All are notably dense.

Crystal System

Hematite: Trigonal; Magnetite: Isometric; Goethite: Orthorhombic; Limonite: Amorphous/Cryptocrystalline

Color

Reddish-brown, black, steel-gray, yellowish-brown

Luster

Metallic, submetallic, dull, earthy

Transparency

Opaque

Fracture

Conchoidal to uneven (hematite, magnetite), splintery (goethite), earthy (limonite)

Cleavage

None (magnetite, goethite, limonite); Parting (hematite)

Composition

Primarily iron oxides (Fe2O3, Fe3O4) and hydrated iron oxides (FeO(OH)·nH2O)

Physical characteristics

• Crystal Habit: Massive, granular, botryoidal, reniform, oolitic, pisolitic, micaceous (specular hematite), octahedral (magnetite)
• Cleavage Type: None to poor parting (hematite)
• Fracture Type: Conchoidal, uneven, splintery, earthy
• Tenacity: Brittle
• Luster Type: Metallic, submetallic, dull, earthy

Explore Iron Ore