Crystals and the Mohs Scale
Jimble Stevens
Mohs scale is a scale of the scratchability of stones when they are scratched by another substance.
1 is very soft e.g. Talc, and 10 is very hard e.g. Diamond.
It is a good guide to the general toughness of the stone and it’s ability to withstand impact or pressure..and whether you should have it in a pouch in your pocket or if it’s fine rolling about next to your keys.
Generally, any crystal that has a Mohs rating of 6 or higher can safely be cleaned in water.
Mohs Scale of Mineral Hardness
| Hardness | Example |
|---|---|
| 10 | Diamond. |
| 9 | Corundum, Ruby, Sapphire, Star Ruby, Star Sappire, Star Ruby. |
| 8 | Beryl, Emerald, Topaz, Rutile Topaz, Imperial Topaz, Mystic Topaz, Chrysoberyl, Alexandrite. |
| 7.5 | Garnet, Goshenite, Cats Eye Aquamarine, Morganite, Beryl, Aquamarine, Emerald. |
| 7 | Clear Quartz,Tigers Eye, Amethyst, Citrine, Agate, Rose Quartz, Jasper, Citrine, Agate, Garnet, Mookite, Smoky Quartz, Tourmaline, Danburite, Ametrine, Aventurine, Rutile Quartz, Kunzite. |
| 6 | Moonstone, Labradorite, Spectrolite, Carnelian, Opalite, Peridot, Fire Opal, Star Moonstone, Jadite, Star Sunstone, Prehnite, Kyanite, Amazonite, Chrysoprase, Chalcedony, Zircon, Bloodstone. |
| 5 | Apatite, Apophyllite, Haematite, Obsidian, Cats Eye Apatite, Star Diopside, Turquoise, Lapis Lazuli, Snowflake Obsidian, Sodalite, Opal, Rhodonite. |
| 4 | Fluorite, Rhodocrosite, Ammolite, Larimar, Charoite. |
| 3 | Calcite, Celestite, Cerussite, Coral, Azurite, Malachite. |
| 2 | Selenite (Gypsum), Chrysocolla, Amber, Lepidolite, Pearl. |
| 1 | Talc. |
To give an idea of day to day items a few handy objects that also fit in the Mohs scale are:
- A fingernail is 2½,
- a penny is just under 3,
- a knife blade is 5½,
- glass is 5½,
- a good steel file is 6½.
There are hardly any day to day objects that are more than a 7.
