Five hundred million years ago, during the Cambrian era, much of eastern North America was covered by a shallow sea. As the sand and muck at the bottom of the ocean metamorphosed into the sedimentary rock known as limestone, seawater trickled into holes and cracks in the rock, where the heat and pressure forced the minerals in the water out of solution, so that crystals began to grow inside the rock. Over time, some crystals weathered out of the rock and can be found loose in the dirt, while others are still inside the cavities ("on matrix") where they formed all those years ago. You can find these beautiful specimens either way, it just depends on how hard you want to work. The rock where all Herkimer diamonds formed is known technically as "Little Falls Dolostone", a dolomitic limestone composed of magnesium calcium carbonate, and it's hard-rock mining anywhere you go.

Serious rock-breakers will need large sledge hammers, from 8 to 20 lbs, and lots of chisels and pry bars. More leisurely collectors can dig in the dirt pile with small garden tools such as rakes, trowels, shovels, and screens. Tweezers and whisk brooms come in handy. Either way, eye protection is important, and gloves and work boots are good also.

Large specimens tend to have internal fractures and dings; the gemmy crystals are more likely to be 1" or less. 

• World-Famous Brilliant "Herkimer Diamond" Quartz Crystals.
• Affordable Fun & Enjoyment:
  Daily Rates -
  Adults: $10.00
  Children (5-14 Years Old): $8.00 
  Children (4 Years Old and Under): Free
• Digging Hours 8a.m. to 8 p.m. or dusk, April 15th - October 15th
• Group Rates Available
• Bring Your Own Tools Or Rent Ours
• Keep all you find
• Picnic Area & Playground
• Rock & Mineral Shop
• Tax is now included with all prices