How to identify Botryoidal Hematite

To correctly identify Botryoidal Hematite (Hematite (Fe2O3) with botryoidal habit), 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

   Steel-gray to black, sometimes with an iridescent tarnish. Internally, it can be reddish-brown.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Metallic to submetallic, sometimes dull in massive forms.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Characteristically rounded, globular, or mammillary aggregates, resembling bunches of grapes or kidneys.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Botryoidal, mammillary, reniform (kidney-shaped). Individual crystals are typically microscopic within the aggregates.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None observed in botryoidal forms due to its aggregate nature; however, hematite itself has no true cleavage but exhibits parting on {0001} and {1011}.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Hydrothermal veins, sedimentary deposits (e.g., banded iron formations), contact metamorphic zones, and as a secondary mineral in oxidized zones of ore deposits. Often found in cavities or open spaces where precipitation can occur freely.

Key Facts

Hardness

5.5 - 6.5 on Mohs scale

Specific Gravity

5.26 g/cm³ (pure hematite)

Crystal System

Trigonal

Color

Steel-gray, black, reddish-brown (in thin splinters or powder)

Luster

Metallic to submetallic, dull to earthy in some varieties

Transparency

Opaque

Fracture

Uneven to subconchoidal

Cleavage

None (parting on {0001} and {1011} is observed in some crystalline forms, but not typically in botryoidal aggregates)

Composition

Iron(III) oxide (Fe2O3)

Physical characteristics

• Crystal Habit: Botryoidal, mammillary, reniform, massive, micaceous (specularite), oolitic, columnar, stalactitic, tabular crystals.
• Cleavage Type: None (parting is present in some crystalline forms)
• Fracture Type: Uneven to subconchoidal
• Tenacity: Brittle
• Luster Type: Metallic to submetallic, dull to earthy

Explore Botryoidal Hematite