How to identify Lepidolite

To correctly identify Lepidolite (K(Li,Al)3(Si,Al)4O10(F,OH)2), 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 lilac, pink, or purple; less commonly gray, white, or yellowish. The color is often due to trace amounts of manganese.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous to pearly on cleavage surfaces.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Often found in scaly aggregates, 'books' of stacked flakes, or radiating masses. Individual crystals are tabular.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Monoclinic, typically forming pseudohexagonal tabular crystals, often in aggregates. Can also be massive or granular.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Perfect basal cleavage (001), allowing it to be split into thin, flexible, and elastic sheets.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Predominantly found in granitic pegmatites, especially those enriched in lithium. Also occurs in high-temperature hydrothermal veins and greisens associated with granitic intrusions.

Key Facts

Hardness

2.5-3.5 on the Mohs scale

Specific Gravity

2.8-2.9 g/cm³

Crystal System

Monoclinic

Color

Lilac, pink, purple, gray, white, yellowish

Luster

Vitreous to pearly

Transparency

Transparent to translucent

Fracture

Uneven to splintery (not typically observed due to perfect cleavage)

Cleavage

Perfect basal cleavage on {001}

Composition

Potassium lithium aluminum silicate hydroxide fluoride

Physical characteristics

• Crystal Habit: Pseudohexagonal tabular crystals, often in scaly aggregates, 'books', or radiating masses. Can also be massive or granular.
• Cleavage Type: Perfect basal cleavage (one direction)
• Fracture Type: Uneven to splintery (rarely observed)
• Tenacity: Flexible and elastic (thin sheets)
• Luster Type: Vitreous to pearly

Explore Lepidolite