How to identify Botryoidal Hematite with Quartz

To correctly identify Botryoidal Hematite with Quartz (Fe2O3 (hematite) and SiO2 (quartz)), 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, sometimes reddish-brown. Quartz: Colorless, white, milky, smoky, or purple (amethyst).

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Hematite: Metallic to submetallic, dull in earthy varieties. Quartz: Vitreous (glassy).

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Botryoidal (grape-like, mammillary) masses of hematite, often with crystalline quartz lining cavities or intergrown.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Hematite: Botryoidal, reniform, mammillary, massive. Quartz: Hexagonal prisms with pyramidal terminations, massive, granular.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Hematite: No true cleavage, but parting on {0001} and {1011}. Quartz: None.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Hydrothermal veins, vugs in igneous and metamorphic rocks, sedimentary iron formations, and as secondary mineralization in various rock types.

Key Facts

Hardness

Hematite: 5-6.5 (Mohs). Quartz: 7 (Mohs).

Specific Gravity

Hematite: 5.26 g/cm³. Quartz: 2.65 g/cm³.

Crystal System

Hematite: Trigonal. Quartz: Trigonal.

Color

Hematite: Steel-gray, black, reddish-brown. Quartz: Colorless, white, milky, smoky, purple, etc.

Luster

Hematite: Metallic to submetallic, dull. Quartz: Vitreous.

Transparency

Hematite: Opaque. Quartz: Transparent to translucent.

Fracture

Hematite: Uneven to subconchoidal. Quartz: Conchoidal.

Cleavage

Hematite: None, but parting on {0001} and {1011}. Quartz: None.

Composition

Hematite: Iron(III) oxide (Fe2O3). Quartz: Silicon dioxide (SiO2).

Physical characteristics

• Crystal Habit: Hematite: Botryoidal, reniform, mammillary, massive, tabular, micaceous (specularite). Quartz: Prismatic, massive, granular, cryptocrystalline (chalcedony).
• Cleavage Type: Hematite: Parting on {0001} and {1011}. Quartz: None.
• Fracture Type: Hematite: Uneven to subconchoidal. Quartz: Conchoidal.
• Tenacity: Hematite: Brittle. Quartz: Brittle.
• Luster Type: Hematite: Metallic to submetallic, dull. Quartz: Vitreous.

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