How to identify Sulfur

To correctly identify Sulfur (S), 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

   Bright yellow, lemon yellow, brownish yellow, greenish yellow, or grayish yellow. Can be discolored by impurities.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Resinous to greasy, sometimes adamantine on crystal faces.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Typically massive, earthy, or powdery. Crystalline forms show distinct faces.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Orthorhombic dipyramidal crystals are common, often forming bipyramids, tabular crystals, or thick prisms. Also occurs as massive, reniform, stalactitic, or encrusting forms.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Poor to indistinct on {001}, {110}, and {111}. Fracture is more characteristic.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Volcanic fumaroles and solfataras, hot springs, sedimentary evaporite deposits (especially associated with gypsum/anhydrite and hydrocarbons in salt domes), and as an alteration product of sulfide minerals.

Key Facts

Hardness

1.5-2.5 (Mohs scale)

Specific Gravity

2.07-2.09 g/cm³

Crystal System

Orthorhombic

Color

Bright yellow, lemon yellow, brownish yellow, greenish yellow, grayish yellow

Luster

Resinous to greasy, sometimes adamantine

Transparency

Transparent to translucent

Fracture

Conchoidal to uneven

Cleavage

Poor to indistinct on {001}, {110}, {111}

Composition

Elemental Sulfur (S)

Physical characteristics

• Crystal Habit: Dipyramidal, tabular, prismatic, massive, reniform, stalactitic, encrusting, powdery
• Cleavage Type: Poor/Indistinct
• Fracture Type: Conchoidal to uneven, very brittle
• Tenacity: Brittle
• Luster Type: Resinous to greasy

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