How to identify Iron Ore (Hematite-Goethite type)

To correctly identify Iron Ore (Hematite-Goethite type) (Hematite (Fe2O3) and Goethite (FeO(OH))), 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 to black (specular hematite), reddish-brown to red (earthy hematite). Goethite: Yellowish-brown to dark brown, sometimes black.

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

   Can be massive, granular, oolitic, pisolitic, botryoidal, reniform, or earthy. Often dense and heavy.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Hematite: Rhombohedral, tabular, micaceous (specularite), or massive. Goethite: Orthorhombic, typically acicular, fibrous, botryoidal, stalactitic, or massive.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Hematite: No true cleavage, but parting may be observed parallel to the basal pinacoid or rhombohedral faces. Goethite: Perfect {010} cleavage, but rarely observed in massive forms.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Banded Iron Formations (BIFs) in ancient cratons, lateritic weathering profiles in tropical regions, bog iron deposits in wetlands, and hydrothermal alteration zones.

Key Facts

Hardness

Hematite: 5-6.5 on Mohs scale. Goethite: 5-5.5 on Mohs scale.

Specific Gravity

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

Crystal System

Hematite: Trigonal. Goethite: Orthorhombic.

Color

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

Luster

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

Transparency

Opaque.

Fracture

Hematite: Uneven to subconchoidal. Goethite: Uneven.

Cleavage

Hematite: None (parting present). Goethite: Perfect {010} (rarely observed).

Composition

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

Physical characteristics

• Crystal Habit: Hematite: Rhombohedral, tabular, micaceous, massive, botryoidal, reniform. Goethite: Acicular, fibrous, botryoidal, stalactitic, massive, earthy.
• Cleavage Type: Hematite: No true cleavage, but parting on {1011} and {0001}. Goethite: Perfect {010} cleavage, but often not visible in massive aggregates.
• Fracture Type: Hematite: Uneven to subconchoidal. Goethite: Uneven.
• Tenacity: Brittle.
• Luster Type: Hematite: Metallic, submetallic, dull, earthy. Goethite: Adamantine, silky, dull, earthy.

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