How to identify Unidentified Mineral Fragment

To correctly identify Unidentified Mineral Fragment (Unknown Mineral), 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

   Highly variable; can be any color or colorless. Color alone is rarely diagnostic.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Highly variable; can be metallic, submetallic, vitreous (glassy), resinous, greasy, pearly, silky, or dull/earthy.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Highly variable; can be granular, massive, fibrous, platy, botryoidal, etc. Surface texture may provide clues.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   If present, crystal habit (e.g., prismatic, tabular, acicular, anhedral) is a crucial diagnostic feature. However, fragments may not show distinct crystal forms.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Presence or absence of cleavage, and the number of cleavage planes and their angles, are critical. Can be perfect, good, fair, poor, or absent.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   The geological context where the fragment was found (e.g., igneous intrusion, sedimentary bed, metamorphic terrain, hydrothermal vein) provides vital clues about its potential identity.

Key Facts

Hardness

Unknown (requires testing, Mohs scale 1-10)

Specific Gravity

Unknown (requires testing, typically 1-20 g/cm³)

Crystal System

Unknown (requires identification, can be any of the 7 crystal systems or amorphous)

Color

Unknown (highly variable)

Luster

Unknown (highly variable)

Transparency

Unknown (can be transparent, translucent, or opaque)

Fracture

Unknown (can be conchoidal, uneven, splintery, hackly, earthy)

Cleavage

Unknown (can be absent, poor, distinct, good, perfect, in 1, 2, 3, 4, or 6 directions)

Composition

Unknown (requires chemical analysis)

Physical characteristics

• Crystal Habit: Unknown (if present, can be massive, granular, crystalline, fibrous, etc.)
• Cleavage Type: Unknown (if present, can be basal, prismatic, pinacoidal, rhombohedral, cubic, octahedral, dodecahedral)
• Fracture Type: Unknown (can be conchoidal, uneven, splintery, hackly, earthy)
• Tenacity: Unknown (can be brittle, malleable, ductile, sectile, flexible, elastic)
• Luster Type: Unknown (can be metallic, submetallic, vitreous, resinous, greasy, pearly, silky, dull/earthy)

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