Adamant

Ezekiel 3:9:  As an adamant harder than flint have I made thy forehead: fear them not, neither be dismayed at their looks, though they be a rebellious house.

Zechariah 7:12:  Yea, they made their hearts as an adamant stone, lest they should hear the law, and the words which the LORD of hosts hath sent in his spirit by the former prophets: therefore came a great wrath from the LORD of hosts.

Literal Hebrew translations from Strong's:

  1. thorn(s), adamant, flint

    1. throns, thorn-bushes

    2. adamant (as sharp)

    3. a sharp stone, flint

  2. perhaps a diamond

Adamant is any especially hard substance, whether diamond, other gem or metal. Both adamant and diamond derive from the Greek word adamas, meaning untameable.
    Since diamond is now used exclusively for the hardest gem, adamant has mostly poetic or figurative use. As an increasingly archaic word, it - and its adjectival form adamantine - is especially often seen in fantasy fiction. For instance, in Tolkien's Lord of the Rings, Galadriel's ring Nenya is also named the "Ring of Adamant".

 

ADAMANT AGATE ALABASTER AMBER
AMETHYST ANTIMONY ASPHALT BDELLIUM
BERYL BITUMEN BRASS BRIMSTONE
BRONZE CARBUNCLE CARNELION CHALCEDONY
CHALK CHRYSOLITE CHRYSOPRASE CLAY
COAL COPPER CORAL CRYSTAL
DIAMOND EMERALD FLINT GLASS
GOLD HYACINTH IRON JACINTH
JADE JASPER LAPIS LAZULI LEAD
LIGURE LIME MALACHITE MARBLE
NITER ONYX PEARL PITCH
QUARTZ RUBY SALT SAPPHIRE
SARDINE STONE SARDIUS SARDONYX SILVER
SLIME SOLDER STIBIC-STONE SULFUR
TIN TOPAZ TURQUOISE VERMILION
WATER ZIRCON   Gem Home