Domingo says that the Geodes are gifts from Zemi the volcano spirit. Geodes are found by expanding to new plots of land. A new Geode looks like this:
Use Tools to extract crystals from the Geodes.
Geodes randomly give three types of crystals:
orange crystals
blue crystals
purple crystals
Each Tool is better for getting a specific color of crystal from a Geode:
Pickaxe = orange crystals
Mallet = blue crystals
Shovel = purple crystals
Get more Tools by completing guest orders at the Order Board, or buy with Gems.
Using a Tool on a Geode starts the process, but it takes a while before the crystals are released and can be collected. The Geode glows while preparing to be collected.
Tap on the Geode to see when it will be ready to be collected. You can use Sunshine or Gems to rush the process.
Once the Geode is ready for collection, it will sparkle.
Tap on it and collect your crystals. You'll receive XP, crystals, and sometimes other random rewards such as Sunshine or Quick-Sand.
About Crystals: Crystals are used to craft valuable Goods at the Jeweler.
You can use Goods made with crystals to complete special orders at the Order Board that reward you with Sand Dollars, and for other special uses.
You'll be able to collect many crystals from each Geode, but they don't last forever. Eventually a Geode will run out of crystals and disappear. This is a Geode about halfway through its life:
And this is a Geode that will soon disappear:
When your Geode looks like this, it's time to look for another one! Keep expanding to new land plots to find Geodes.