How to identify Iron Ore

To correctly identify Iron Ore (Hematite/Goethite (Iron Oxide/Hydroxide)), 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

   Hematite: Steel-gray, reddish-brown, black. Goethite: Yellowish-brown, dark brown, blackish-brown.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Hematite: Metallic to dull/earthy. Goethite: Adamantine to dull/earthy.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Hematite: Can be massive, botryoidal, reniform, micaceous (specular hematite), or oolitic. Goethite: Often massive, fibrous, botryoidal, or stalactitic.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Hematite: Trigonal system, typically tabular, rhombohedral, or massive. Goethite: Orthorhombic system, typically acicular, fibrous, or massive.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Hematite: No true cleavage, but parting may be observed along rhombohedral planes. Goethite: Perfect cleavage on {010}, but rarely observed in massive forms.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in Banded Iron Formations (BIFs), lateritic soils, bog iron deposits, hydrothermal veins, and as alteration products in various rock types. BIFs are characteristic of Precambrian shield areas. Lateritic deposits are common in tropical and subtropical regions.

Key Facts

Hardness

Hematite: 5-6.5 (Mohs). Goethite: 5-5.5 (Mohs).

Specific Gravity

Hematite: 5.26 g/cm³. Goethite: 3.3-4.3 g/cm³.

Crystal System

Hematite: Trigonal. Goethite: Orthorhombic.

Color

Hematite: Steel-gray, reddish-brown, black. Goethite: Yellowish-brown, dark brown.

Luster

Hematite: Metallic to dull/earthy. Goethite: Adamantine to dull/earthy.

Transparency

Opaque.

Fracture

Hematite: Uneven to subconchoidal. Goethite: Uneven.

Cleavage

Hematite: None (parting common). Goethite: Perfect on {010}, but rarely observed.

Composition

Hematite: Iron(III) oxide (Fe2O3). Goethite: Iron(III) oxyhydroxide (FeO(OH)).

Physical characteristics

• Crystal Habit: Hematite: Rhombohedral, tabular, massive, botryoidal, reniform, micaceous (specular). Goethite: Acicular, fibrous, massive, botryoidal, stalactitic.
• Cleavage Type: Hematite: No true cleavage, but parting on {1011} is common. Goethite: Perfect on {010}, but often obscured by massive habit.
• Fracture Type: Uneven to subconchoidal.
• Tenacity: Brittle.
• Luster Type: Hematite: Metallic, submetallic, dull, earthy. Goethite: Adamantine, silky, dull, earthy.

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