How to identify Galena in Quartz

To correctly identify Galena in Quartz (Galena (PbS) with Quartz (SiO2)), 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

   Galena: Lead-gray to silvery-gray, often tarnishing to a dull gray. Quartz: Colorless, white, milky, or various other colors depending on impurities.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Galena: Metallic, bright. Quartz: Vitreous (glassy) to greasy.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Galena: Often granular or massive, but can form distinct cubic or octahedral crystals. Quartz: Can be massive, granular, or form well-developed prismatic crystals.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Galena: Cubic, cubo-octahedral, or octahedral crystals. Quartz: Hexagonal prisms terminating in hexagonal pyramids.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Galena: Perfect cubic cleavage in three directions at 90 degrees, producing characteristic stair-step fractures. Quartz: No cleavage, conchoidal fracture.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Hydrothermal veins, replacement deposits, and sedimentary exhalative (SEDEX) deposits, often associated with other sulfide minerals like sphalerite, pyrite, and chalcopyrite, and gangue minerals such as calcite, fluorite, and barite.

Key Facts

Hardness

Galena: 2.5-2.75 on Mohs scale; Quartz: 7 on Mohs scale

Specific Gravity

Galena: 7.4-7.6; Quartz: 2.65

Crystal System

Galena: Isometric (cubic); Quartz: Trigonal

Color

Galena: Lead-gray, silvery-gray; Quartz: Colorless, white, milky, various other colors

Luster

Galena: Metallic; Quartz: Vitreous to greasy

Transparency

Galena: Opaque; Quartz: Transparent to translucent

Fracture

Galena: Subconchoidal to uneven; Quartz: Conchoidal

Cleavage

Galena: Perfect cubic (3 directions at 90 degrees); Quartz: None

Composition

Galena: Lead sulfide (PbS); Quartz: Silicon dioxide (SiO2)

Physical characteristics

• Crystal Habit: Galena: Cubic, cubo-octahedral, octahedral, massive, granular; Quartz: Prismatic, massive, granular, cryptocrystalline
• Cleavage Type: Galena: Perfect cubic; Quartz: None
• Fracture Type: Galena: Subconchoidal to uneven; Quartz: Conchoidal
• Tenacity: Galena: Brittle; Quartz: Brittle
• Luster Type: Galena: Metallic; Quartz: Vitreous to greasy

Explore Galena in Quartz