How to identify Malachite with Limonite

To correctly identify Malachite with Limonite (Cu2(CO3)(OH)2 (Malachite) with FeO(OH)·nH2O (Limonite)), 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

   Malachite is typically bright green, often banded in shades of green. Limonite ranges from yellow-brown to dark brown, reddish-brown, or ochre.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Malachite can be silky (fibrous), vitreous (crystalline), or dull (massive). Limonite is typically dull, earthy, or submetallic.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Malachite often forms botryoidal, mammillary, stalactitic, or fibrous aggregates. Limonite is commonly massive, earthy, or concretionary.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Malachite rarely forms distinct crystals, usually occurring as radiating fibrous aggregates or massive forms. Limonite is amorphous or cryptocrystalline, never forming distinct crystals.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Malachite has perfect cleavage in one direction, but it is rarely observed due to its common habit. Limonite has no cleavage.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in the oxidized zones of copper sulfide deposits, often associated with other secondary copper minerals (e.g., azurite, chrysocolla) and iron oxides/hydroxides.

Key Facts

Hardness

Malachite: 3.5-4 on Mohs scale. Limonite: 4-5.5 on Mohs scale.

Specific Gravity

Malachite: 3.9-4.03. Limonite: 2.7-4.3 (variable due to amorphous nature and water content).

Crystal System

Malachite: Monoclinic. Limonite: Amorphous to cryptocrystalline (no defined crystal system).

Color

Malachite: Bright green, banded green. Limonite: Yellow-brown, reddish-brown, ochre.

Luster

Malachite: Silky, vitreous, dull. Limonite: Dull, earthy, submetallic.

Transparency

Malachite: Translucent to opaque. Limonite: Opaque.

Fracture

Malachite: Uneven to subconchoidal. Limonite: Uneven, earthy.

Cleavage

Malachite: Perfect in one direction {201}. Limonite: None.

Composition

Malachite: Copper carbonate hydroxide. Limonite: Hydrated iron oxide.

Physical characteristics

• Crystal Habit: Malachite: Botryoidal, mammillary, stalactitic, fibrous, massive. Limonite: Massive, earthy, concretionary, stalactitic.
• Cleavage Type: Malachite: Perfect {201}. Limonite: None.
• Fracture Type: Malachite: Uneven to subconchoidal. Limonite: Uneven, earthy.
• Tenacity: Malachite: Brittle. Limonite: Brittle to friable.
• Luster Type: Malachite: Silky, vitreous, dull. Limonite: Dull, earthy, submetallic.

Explore Malachite with Limonite