How to identify Iron Ore

To correctly identify Iron Ore (Iron Oxide (e.g., Hematite, Goethite)), 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

   Varies significantly: Hematite can be reddish-brown, steel-gray, or black. Magnetite is black. Goethite/Limonite are yellowish-brown to dark brown. Siderite is typically yellowish-brown to gray.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Hematite: metallic to dull/earthy. Magnetite: metallic to submetallic. Goethite/Limonite: earthy to silky. Siderite: vitreous to pearly.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Can be massive, granular, oolitic, botryoidal, reniform, or specular (micaceous hematite).

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Hematite: tabular, rhombohedral, botryoidal, massive. Magnetite: octahedral, dodecahedral, massive. Goethite: acicular, fibrous, botryoidal, massive. Siderite: rhombohedral, massive.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Hematite: no true cleavage, but parting on {0001} and {1011}. Magnetite: no cleavage, but parting on {111}. Goethite: perfect on {010}. Siderite: perfect rhombohedral on {1011}.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Banded Iron Formations (BIFs) in ancient marine sedimentary basins; lateritic deposits in tropical and subtropical regions; magmatic segregations in mafic and ultramafic igneous rocks; hydrothermal veins; bog iron deposits in swamps and bogs.

Key Facts

Hardness

Hematite: 5-6. Magnetite: 5.5-6.5. Goethite: 5-5.5. Siderite: 3.5-4.5 (Mohs scale)

Specific Gravity

Hematite: 4.9-5.3. Magnetite: 5.18. Goethite: 3.3-4.3. Siderite: 3.96 (g/cm³)

Crystal System

Hematite: Trigonal. Magnetite: Isometric. Goethite: Orthorhombic. Siderite: Trigonal.

Color

Variable: Reddish-brown, black, steel-gray, yellowish-brown, gray.

Luster

Metallic, submetallic, earthy, dull, silky, vitreous, pearly.

Transparency

Opaque (most forms), translucent (thin splinters of hematite/goethite).

Fracture

Conchoidal to uneven (hematite, magnetite), uneven (goethite, siderite).

Cleavage

Hematite: no true cleavage, parting. Magnetite: no cleavage, parting. Goethite: perfect on {010}. Siderite: perfect rhombohedral.

Composition

Iron oxides (Fe2O3, Fe3O4, FeO(OH)) or iron carbonate (FeCO3).

Physical characteristics

• Crystal Habit: Massive, granular, botryoidal, reniform, oolitic, tabular, rhombohedral, octahedral, acicular, fibrous.
• Cleavage Type: Absent to perfect rhombohedral, or parting.
• Fracture Type: Conchoidal, uneven, splintery.
• Tenacity: Brittle.
• Luster Type: Metallic, submetallic, earthy, dull, silky, vitreous, pearly.

Explore Iron Ore