Crystals Hardness Help

Crystal

Crystalline structure

Mohs’ hardness

• se industrial (I) ornamental (O) gemstone (G)

Specific gravity

Agate

Hexagonal

6.5–7

O, G

2.6–2.65

Alexandrite

Orthorhombic

8.5

G

3.7

Alamandine

Cubic

6.5–7.5

I, G

4–4.2

Amazonite

Triclinic

6–6.5

O, G

2.56–2.58

Amethyst

Hexagonal

7

O, G

2.63–2.65

Andalusite

Orthorhombic

7–7.5

I, G

3.2

Anglesite

Orthorhombic

2.5–3

O

6.3–6.4

Anhydrite

Orthorhombic

3–3.5

I

2.98

Antimony

Trigonal/hexagonal

3–3.5

I

6.7

Apatite

Hexagonal

5

I

3.1–3.2

Aquamarine

Hexagonal

7.5–8

G

2.67–2.7

Argentite

Cubic

2–2.5

I

7.2–7.4

Autunite

Tetragonal

2–2.5

I

3–3.2

Axinite

Triclinic

6.5–7

G

3.4–3.65

Azurite

Monoclinic

3.5–4

I

3.7–3.9

Barite

Orthorhombic

3–3.5

I

4.5

Bauxite

Aggregate of various crystal types

1–3

I

2.0–2.7

Benitoite

Hexagonal

6–6.5

G

3.65–3.68

Bentonite

Monoclinic

1

I

1.2–2.7

Beryl

Hexagonal

7.5–8

G

2.65–2.75

Bismuth

Hexagonal

2–2.5

I

9.7–9.8

Borax

Monoclinic

2–2.5

I

1.7

Brazilianite

Monoclinic

5.5

G

2.9

Brucite

Hexagonal

2.5

I

2.3–2.5

Calcite

Hexagonal

3

I, O, G

2.71

Cassiterite

Tetragonal

6–7

I

6.8–7.1

Celestine

Orthorhombic

3–3.5

I, O

3.96–3.98

Cerussite

Orthorhombic

3–3.5

I, G

6.4–6.6

Chalcedony

Hexagonal

6.5–7

G

2.59–2.64

Chalcocite

Orthorhombic

2.5–3

I

5.5–5.8

Chalcopyrite

Tetragonal

3.5–4

I

4.1–4.3

Chromite

Cubic

5.5

I

4.5–4.8

Cinnabar

Hexagonal

2–2.5

I

8.0–8.2

Citrine

Hexagonal

7

G

2.65

Colemanite

Monoclinic

4.5

I, O

2.42

Copper

Cubic

2.5–3

I, O

8.9

Crocoite

Monoclinic

2.5–3

I

6.0

Cuprite

Cubic

3.5–4

I, O, G

6.14

Danburite

Orthorhombic

7–7.5

G

2.97–3

Diamond

Cubic

10

I, G

3.52

Diopside

Monoclinic

5–6

G

3.27–3.31

Dioptase

Hexagonal

5

G

3.3–3.35

Dolomite

Hexagonal

3.5–4

I, O

2.85–2.95

Emerald

Hexagonal

7.5–8

G

2.7–2.78

Enstatite

Orthorhombic

5.5

I

3.26–3.28

Epidote

Monoclinic

6–7

O, G

3.3–3.5

Fluorite

Cubic

4

I

3.1–3.3

Galena

Cubic

2.5–3

I, O

7.58

Glauberite

Monoclinic

2.5–3

O

2.8

Goethite

Orthorhombic

5–5.5

I, O

3.3–4.3

Gold

Cubic

2.5

I, O

19.3

Graphite

Hexagonal

1–2

I

2.1–2.3

Grossular

Cubic

6.5–7.5

G

3.6–3.7

Gypsum

Monoclinic

2

I

2.35

Halite

Cubic

2

I

2.1–2.2

Hematite

Hexagonal

5.5–6.5

I, G

5–5.3

Hemimorphite

Orthorhombic

4.5–5

O, G

3.4–3.5

Hiddenite

Monoclinic

6–7

G

3.16–3.2

Indicolite

Hexagonal

7–7.5

G

3–3.25

Iolite

Orthorhombic

7–7.5

G

2.55–2.65

Jadeite (jade)

Monoclinic

6.5–7

O, G

3.33

Jasper

Hexagonal

6.5–7

O

2.6–2.9

Kunzite

Monoclinic

6–7

I, G

3.16–3.2

Kyanite

Triclinic

4–7

I

3.65–3.69

Labradorite

Triclinic

6–6.5

O, G

2.7

Lapis

lazuli Cubic

5–6

O

2.4–2.9

Lazulite

Monoclinic

5–6

G

1.6–1.65

Magnetite

Cubic

5.5–6.5

I

5.2

Malachite

Monoclinic

3.5–4

O

4

Manganite

Monoclinic

4

I, O

4.3

Marcasite

Orthorhombic

6–6.5

O

4.92

Mercury

Hexagonal (below –39°C)

0 (room temperature) I

13.6

Microlite

Cubic

5–5.5

I, O

4.3–5.7

Molybdenite

Hexagonal

1–1.5

I

4.6–4.7

Monazite

Monoclinic

5–5.5

I

4.6–5.4

Moonstone

Monoclinic

6–6.5

G

2.62

Morganite

Hexagonal

7.5–8

G

2.65–2.75

Muscovite (mica)

Monoclinic

2–3

I

2.77–2.88

Neptunite

Monoclinic

5–6

O

3.19–3.23

Niccolite

Hexagonal

5–5.5

I

7.5–7.8

Olivine (peridot)

Orthorhombic

6.5–7

G

3.27–4.32

Opal

Noncrystalline silica

5.5–6.5

G

1.98–2.1

Orthoclase

Monoclinic

6

I, G

2.5–2.6

Peridot (chrysolite)

Orthorhombic

6.5–7

G

3.3–4.2

Phenacite

Hexagonal

7.5–8

G

3

Platinum

Cubic

4–4.5

I, O

21.4

Prehnite

Orthorhombic

6–6.5

I

2.8–2.95

Pyrite

Cubic

6–6.5

I

5.02

Pyrrhotite

Hexagonal

3.5–4.5

I

4.6–4.7

Quartz (clear)

Trigonal

7

O, G

2.65

Rhodochrosite

Hexagonal

3.5–4.5

I, O

3.3–3.7

Rhodolite

Cubic

6.5–7.5

O

3.75–3.9

Rhodonite

Triclinic

5.5–6.5

O

3.57–3.76

Rose

quartz Hexagonal

7

O

2.65

Rubellite

Hexagonal

7–7.5

G

3–3.25

Ruby

Hexagonal

9

I, G

4

Sapphire

Hexagonal

9

I, G

4

Scheelite

Tetragonal

4.5–5

I

6.10

Silver

Cubic

2.5–3

I, O

10.5

Smithsonite

Hexagonal

4–5

I, O

4.3–4.5

Sodalite

Cubic

5.5–6

O, G

2.13–2.3

Spessartite

Cubic

6.5–7.5

G

4.2

Sphalerite

Cubic

3.5–4

I

3.9–4.2

Spinel

Cubic

8

G

3.6

Staurolite

Monoclinic

7–7.5

G

3.7–3.8

Stibnite

Orthorhombic

2

I

4.6–4.7

Strontianite

Orthorhombic

3.5

I

3.78

Sulfur

Orthorhombic

1.5–2.5

I

2.0–2.1

Sylvite

Cubic

2

I

1.99

Talc

Monoclinic

1

I, O

2.5–2.8

Tanzanite

Orthorhombic

6.5–7

G

3.1–3.4

Tiger

eye Hexagonal

7

O, G

2.65–2.7

Topaz

Orthorhombic

8

G

3.5–3.6

Torbernite

Tetragonal

2–2.5

I

2.68

Tourmaline

Hexagonal

7–7.5

O, G

3–3.25

Turquoise

Triclinic

5–6

O, G

2.6–2.8

• raninite

Cubic

5–6

I

7.5–10

Variscite

Orthorhombic

4–5

O

2.4–2.6

Vermiculite

Monoclinic

2–3

I

2.4–2.7

Vesuvianite

Tetragonal

6.5

G

3.27–3.45

Zircon

Tetragonal

6.5–7

I, G

4.7