How to identify Iron Ore

To correctly identify Iron Ore (Hematite/Goethite (weathered iron oxides)), 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, botryoidal, reniform, oolitic, or earthy. Specular hematite has a micaceous or platy texture. Goethite often forms stalactitic or radiating fibrous aggregates.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Hematite: Rhombohedral, tabular, or massive. Goethite: Orthorhombic, typically acicular, fibrous, or massive.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

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

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Banded Iron Formations (BIFs), lateritic weathering profiles, bog iron deposits, hydrothermal veins, sedimentary beds, and as alteration products in various rock types.

Key Facts

Hardness

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

Specific Gravity

Hematite: 4.9-5.3. Goethite: 3.3-4.3.

Crystal System

Hematite: Trigonal. Goethite: Orthorhombic.

Color

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

Luster

Hematite: Metallic, submetallic, dull, earthy. Goethite: Adamantine, silky, dull, earthy.

Transparency

Opaque

Fracture

Hematite: Uneven to subconchoidal. Goethite: Uneven.

Cleavage

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

Composition

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

Physical characteristics

• Crystal Habit: Hematite: Rhombohedral, tabular, massive, botryoidal, reniform, micaceous (specularite), earthy. Goethite: Acicular, fibrous, radiating, stalactitic, massive, botryoidal, earthy.
• Cleavage Type: Hematite: None (parting on {1011}). Goethite: Perfect on {010}.
• Fracture Type: Uneven to subconchoidal
• Tenacity: Brittle
• Luster Type: Metallic, submetallic, adamantine, silky, dull, earthy

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