Cheapest priced copy (The Lost Caverns of Ixalan): $2.79 at Card Kingdom, near mint, their price list as of .
Diamond Pick-Axe 
Artifact — Equipment · Uncommon · The Lost Caverns of Ixalan · #143
Indestructible (Effects that say "destroy" don't destroy this Equipment.)
Equipped creature gets +1/+1 and has "Whenever this creature attacks, create a Treasure token." (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
Equip {2}
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
2 printings · $2.79 to $3.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The Lost Caverns of Ixalan | 143 | Uncommon | $2.79 | $3.99 |
| The List | LCI-143 | Uncommon | — | — |