Gemstone Identification: MOHS SCALE OF MINERAL HARDNESS

If you’re a fan of gemstone, there’s one name you definetely need to respect.

Friedrich Mohs (1773-1839),German Geologist/mineralogist. Mohs, studied chemistry, mathematics and physics. He started classifying minerals by their physical characteristics, in spite of their chemical composition, as it was done before. He created a hardness scale that is still used as Mohs scale of mineral hardness.

The scale goes from 1 to 10. Diamond is at the top of the scale, with a rating of 10, Talc is the softest, with a rating of 1. You can use minerals of known hardness to determine the relative hardness of any other mineral.

 A mineral of a given hardness will scratch a mineral of a lower number. For example one of your fingernail(2) can scratch a talc(1) specimen or with a broken glass(5) you can scratch a calcite(3) or fluorite(4) specimen.

MOHS SCALE OF MINERAL HARDNESS
Hardness Mineral Everyday equivalent

  • 10 –Diamond synthetic diamond
  • 9   –Corundum ruby
  • 8  — Topaz sandpaper
  • 7  — Quartz steel knife
  • 6  — Orthoclase/Feldspar penknife blade
  • 5  — Apatite glass
  • 4  — Fluorite iron nail
  • 3  — Calcite bronze coin
  • 2  — Gypsum fingernail
  • 1  — Talc baby powder

To use the hardness scale, try to scratch the surface of an unknown sample with a mineral or substance from the hardness scale (these are known samples). If the unknown sample cannot be scratched by calcite (3) but it can be scratched by fluorite(4), then it’s hardness is between 3 and 4. An example of minerals that have a hardness between 3 and 4 are barite, celestite and cerussite(3 to 3.5). You can use this test to distinguish between calcite and barite or between barite and fluorite.

If you wish to test an unknown mineral for hardness remember that the minerals can be damaged and lose value if not scratched properly.
Some Gemstones Hardness
•  Diamond –10
•  Sapphire, Ruby–9
•  Crysoberyl, Alexandrite, Cats eye—8.5
•  Beryl, Emerald, Aquamarine – 7.5-8
•  Zircon – 7.5
•  Tourmaline (Elbaite, Dravite) – 7-7.5
•  Quartz (Amethyst, Citrine) — 7
•  Jadeite 6.5-7
•  Nephrite –6.5-7
•  Garnet (Hessonite, Rhodolite, Spessartine) — 6.6-7.5
•  Lapislazuli– 5-5.5
•  Opal — 5.5-6.5
•  Turquoise — 5-6
•  Feldspars (like Labradorite, Amazonite, Moonstone, or Sunstone)–6-6.5

1 Comment

  1. Hamidah
    Mar 27, 2012

    Without seeing a pirtuce nor in person, this is a bit of a shot in the dark, but let me see if I can help you out.There are (2) Main groupings of Jade: Jadeite Nephrite.From what you are describing, yours seems to be Jadeite the more expensive of the two.However, in recent years, Jadeite has been treated to give it a brighter, more vibrant color. This is sometimes known as Dyed or B Jade. If it is this, it can GREATLY diminish the value. ANd yes, they do set these stones in 18kt.Also, there are several Jade-Like Stones that appear to be JAde, but are not and are very inexpensive. Chrysoprase is one. Sometimes known as Australian Jade, it is literally sold by the pound. My suggestion is to have it at least tested or get an opinion if it is truly Jade.If so, Larger, Apple Green Jade Rings in 18kt can retail in the Thousands of Dollars, but please note, this is Retail and not necessarily what you would be able to sell it for. Especially to a dealer or wholesaler.Hope this helps

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