How to identify Iron Ore

To correctly identify Iron Ore (Hematite or Goethite (likely a mixture)), 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: Reddish-brown, steel-gray, 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

   Can be massive, earthy, oolitic, botryoidal, reniform, or specular (sparkling, platy hematite).

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

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

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Hematite: No true cleavage, but parting on {0001} and {1011}. Goethite: Perfect on {010}.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Banded Iron Formations (BIFs) in ancient cratons, lateritic weathering profiles, hydrothermal veins, sedimentary beds, bog iron deposits.

Key Facts

Hardness

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

Specific Gravity

Hematite: 5.26. Goethite: 3.3-4.3.

Crystal System

Hematite: Trigonal. Goethite: Orthorhombic.

Color

Hematite: Reddish-brown, steel-gray, black. 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}.

Composition

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

Physical characteristics

• Crystal Habit: Hematite: Rhombohedral, tabular, micaceous (specularite), massive, botryoidal, reniform, oolitic, earthy. Goethite: Acicular, fibrous, massive, botryoidal, stalactitic, earthy.
• Cleavage Type: Hematite: No true cleavage, but distinct parting on {0001} and {1011}. Goethite: Perfect on {010}.
• 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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