How to identify Desert Rose

To correctly identify Desert Rose (Gypsum var. Selenite or Barite), 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

   Typically sandy brown, tan, reddish-brown, or off-white due to sand inclusions. Pure gypsum roses can be colorless or white.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous to pearly on crystal faces, dull to earthy on sandy surfaces.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Rough and gritty due to sand inclusions; individual crystal faces can be smooth.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Rosette-like aggregates of tabular or platy crystals, resembling a flower. The 'petals' are often curved or bent.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Gypsum Desert Roses exhibit perfect cleavage in one direction (010), good in another (100), and distinct in a third (011). Barite Desert Roses have perfect cleavage in one direction (001) and good in two others (210, 110). This is often difficult to observe in the aggregate form.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Arid and semi-arid desert environments, particularly in shallow evaporitic basins, playas, and sabkhas where groundwater rich in sulfates evaporates near the surface. They are found embedded in sand, clay, or silt.

Key Facts

Hardness

Gypsum Desert Rose: 2 on Mohs scale. Barite Desert Rose: 3-3.5 on Mohs scale.

Specific Gravity

Gypsum Desert Rose: 2.31-2.33 g/cm³. Barite Desert Rose: 4.3-4.7 g/cm³ (significantly heavier than gypsum).

Crystal System

Gypsum: Monoclinic. Barite: Orthorhombic.

Color

Variable, typically sandy brown, tan, reddish-brown, or off-white due to sand inclusions. Can be colorless or white if pure.

Luster

Vitreous to pearly on crystal faces, dull to earthy on sandy surfaces.

Transparency

Translucent to opaque, depending on sand content and crystal thickness.

Fracture

Uneven to conchoidal (gypsum), uneven (barite).

Cleavage

Gypsum: Perfect on {010}, good on {100}, distinct on {011}. Barite: Perfect on {001}, good on {210} and {110}.

Composition

Gypsum Desert Rose: Hydrous calcium sulfate (CaSO4·2H2O). Barite Desert Rose: Barium sulfate (BaSO4).

Physical characteristics

• Crystal Habit: Rosette-like aggregates of tabular or platy crystals, often with curved or bent 'petals' and significant sand inclusions.
• Cleavage Type: Gypsum: Perfect basal cleavage, good prismatic, distinct clinodomal. Barite: Perfect basal cleavage, good prismatic.
• Fracture Type: Uneven to conchoidal (gypsum), uneven (barite).
• Tenacity: Gypsum: Sectile (can be cut with a knife). Barite: Brittle.
• Luster Type: Vitreous to pearly on crystal faces, dull to earthy on sandy surfaces.

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