How to identify Iron Ore

To correctly identify Iron Ore (Hematite or Goethite (likely concretions or nodules)), 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

   Hematite: Can be massive, botryoidal, reniform, micaceous (specularite), or earthy. Goethite: Often fibrous, botryoidal, stalactitic, or earthy, commonly forming concretions and nodules.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Hematite: Rhombohedral crystals, tabular, massive, botryoidal. Goethite: Orthorhombic crystals, but typically massive, fibrous, or botryoidal.

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

   Hematite: Found in Banded Iron Formations (BIFs), hydrothermal veins, contact metamorphic deposits, and as a weathering product. Goethite: Common in lateritic soils, bog iron deposits, gossans (weathered sulfide deposits), and as concretions in sedimentary rocks.

Key Facts

Hardness

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

Specific Gravity

Hematite: 5.26; Goethite: 3.3-4.3

Crystal System

Hematite: Trigonal; Goethite: Orthorhombic

Color

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

Luster

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

Transparency

Opaque

Fracture

Hematite: Uneven to subconchoidal; Goethite: Uneven

Cleavage

Hematite: None (parting common); Goethite: Perfect on {010} (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 (specularite), earthy. Goethite: Prismatic, acicular, fibrous, botryoidal, stalactitic, massive, earthy, oolitic, concretionary.
• Cleavage Type: Hematite: None, but parting on {1011} is common. Goethite: Perfect on {010}, but often not visible in massive forms.
• 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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