Helpful Charts

Most of the Native Elements are shown in this chart.

Moh's Scale of Relative Hardness:
This scale was developed in 1822 by the Austrian Mineralogist Friedrich Moh. This scale lists 10 minerals in ascending order of scratch resistance:
1. Talc
2. Gypsum
3. Calcite
4. Fluorspar
5. Apatite
6. Feldspar
7. Quartz
8. Topaz
9. Corundum
10. Diamond

It should be noted that the above scale is of "relative" hardness, not "linear". Most of the scale is somewhat linear. Which means each mineral is just a little harder than the next.
There is significantly less difference between 7 and 8 than there is between 9 and 10.
Diamond is actually about 10 times harder than Corundum. So the very end of the scale is way off. However the scale does tell us is that a mineral that can be scratched with calcite has a hardness of less than 3 or a mineral that can be scratched with feldspar, but not with quartz, has a hardness of between 6 to 6½ and so on.

Here are hardness values of some other gems, minerals and things you may have in your collection. You can use some of these things to figure hardness even closer.

Agate-7 Alabaster-2 Amber-2.5-2 Amethyst-7 Ammolite-3.5-1 Amazonite -6 Aventurine-7 Azurite-4 Beryl-7.5-8 Bloodstone-7 Carnelian-7 Catseye Chrysoberyl-8.5 Chalcedony-7 Charoite-6 Chrysoprase-7 Chrysocolla-4-2 Copper Penny 3.5 Coral-4-3 Fingernail-2.5
Fluorite-4-3.5 Garnet-7-7.5 Glass-6.5 Hardened Steel File-6.5 Hematite-6.5-5.5
Howlite-3.5-3 Ivory-3-2 Jadeite-7 Jasper-7 Jet-4-2.5 Knife Blade-5.5 Labradorite-6
Lapis Lazuli-6 Larimar (pectolite)-5 Malachite-4-3.5 Moldavite-5.56.5 Moonstone-6
Nephrite Jade-6.5 to 6 Obsidian-5.5-5 Onyx (calcite)-3 Onyx (quartz)-7 Opal -6.5-5.5
Pearl-4.5-2 Petrified Wood-7 Quartz-7 Rhodochrosite-4 Rhodonite-6.5-5.5 Rose Quartz-7
Sard-7 Serpentine-5.5-2 Smithsonite-5 Sodalite-6-5.5 Star Rubies-9 Star Sapphires-9
Sugilite-6.5-6 Sulpher-1 Sunstone-6 Thomsonite-5.5 to 5 Thulite-7 Tigereye-7
Tourmaline-7.5 to 6.5 Turquoise-5-6 Ulexite-2.5-2 Variscite-5-4-3