Mineral Identification Key

The Mineral Identification Key

Copper, Michigan, Seaman Museum specimen

Table IIC-2a: Nonmetallic Luster; Streak Not Colored; Hardness 2½ to 3; Cleavage Not Prominent; Splinter Will Fuse in a Candle Flame. [Previous Table] [Next Table]

Fusibility Color Hardness Luster Name System Habit SG Notes

Swells and fuses to a glassy
globule in a candle flame Usually Snow-white; Colorless to White or Greyish-white, may be tinted other colors 2 to 2½ Vitreous to resinous BORAX Na₂B₄O₅(OH)₄^.8H₂O Monoclinic Usually in crystalline or granular masses, crystals short
prismatic to somewhat tabular, flattened prisms 1.7 Dissolves in water, has a sweetish, alkaline taste

Small splinters fusible in a candle flame Colorless to White, may be tinted other colors 2½ Vitreous to greasy, has an unusual greasy translucence CRYOLITE
Na₃AlF₆ Monoclinic Usually massively
crystalline to coarse granular, crystal rare and usually pseudo-cubic 2.95 to 3.0 White streak; small clear fragments seem to disappear when placed in water (nearly identical refractive-index)

Small splinters fusible in a candle flame Colorless to White or Greyish-White, may be tinted other colors 3 to 3½ Adamantine to vitreous, may be resinous on cleavage surfaces, may also appear submetallic when dark colored CERUSSITE (Aragonite Group)
PbCO₃ Orthorhombic Usually as crystalline to granular masses, crystals usually tabular in platy clusters or aggregates, may be prismatic, rarely acicular (habit widely varied) 6.55 Cleavage distinct in one direction and good in another, but rarely seen, effervesces in warm acid. Massive material difficult to distinguish from anglesite without testing for CO₃ vs. SO₄. Also see strontianite

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Fusibility	Color	Hardness	Luster	Name	System	Habit	SG	Notes
Swells and fuses to a glassy globule in a candle flame	Usually Snow-white; Colorless to White or Greyish-white, may be tinted other colors	2 to 2½	Vitreous to resinous	BORAX Na₂B₄O₅(OH)₄^.8H₂O	Monoclinic	Usually in crystalline or granular masses, crystals short prismatic to somewhat tabular, flattened prisms	1.7	Dissolves in water, has a sweetish, alkaline taste
Small splinters fusible in a candle flame	Colorless to White, may be tinted other colors	2½	Vitreous to greasy, has an unusual greasy translucence	CRYOLITE Na₃AlF₆	Monoclinic	Usually massively crystalline to coarse granular, crystal rare and usually pseudo-cubic	2.95 to 3.0	White streak; small clear fragments seem to disappear when placed in water (nearly identical refractive-index)
Small splinters fusible in a candle flame	Colorless to White or Greyish-White, may be tinted other colors	3 to 3½	Adamantine to vitreous, may be resinous on cleavage surfaces, may also appear submetallic when dark colored	CERUSSITE (Aragonite Group) PbCO₃	Orthorhombic	Usually as crystalline to granular masses, crystals usually tabular in platy clusters or aggregates, may be prismatic, rarely acicular (habit widely varied)	6.55	Cleavage distinct in one direction and good in another, but rarely seen, effervesces in warm acid. Massive material difficult to distinguish from anglesite without testing for CO₃ vs. SO₄. Also see strontianite