How to Identify an Unopened Geode
To identify an unopened geode, examine a medium-sized rock to see if it's rounder and more egg-shaped than the rocks around it, which could be a sign that it's a geode. Also, carefully inspect the surface of the rock to see if it's bumpy since geodes are typically bumpy on the outside. You can also shake the rock next to your ear to see if you hear rattling inside, which would mean the rock is hollow like a geode.
Consult a geode map. Use a reliable guide map when you search for geodes. Rockhounds have gone before you and can get you into areas where finding a geode is much more likely. Geodes are specific geological formations that only result in particular regions.  Within the United States, geode maps identify areas of the Midwest such as Illinois, Iowa, and Missouri as well as areas in the Southeast such as Kentucky, Tennessee, and South Carolina as common geode locations. Geode maps identify Brazil, Namibia Uruguay, Mexico as top areas around the world where geodes are located. Survey your surroundings for likely geode locations. Learn to identify common signs that you may be searching in a location where geodes are likely to be found. When you are hunting for geodes in nature, look for limestone and basalt rocks. These rocks are often key to the formation of geodes. Geodes are also commonly found in lake or river beds. Geodes are often formed in stratified sedimentary carbonate deposits such as limestones and dolomites. Stratified volcanic deposits such as basalt and tuffs rocks also lead to geode formation. Verify whether you are on private property. Check surrounding signs to ensure you are not scouting for geodes on private property. Before you search for geodes on private property, make sure to ask for permission. Even if you are scouting for geodes on public land, it might be protected by a nature preserve, which would mean you might not be permitted to remove natural items from the property. Look for round rocks. Look for medium-sized rocks that appear to be more round than surrounding rocks. Geodes look a lot like normal rocks but can sometimes have an egg-like shape that distinguishes them. Sharp, pointy rocks rarely contain geodes. Check the surface for bumps. Look for rocks that have a unique, bumpy texture on the exterior. Geodes are rarely perfectly smooth. The texture of a geode's exterior may have a cauliflower-like appearance. Inspect the surface for any signs of minerals inside. Sometimes traces of the inside crystals are visible on the surface. Test whether the rock has a hollow interior. Pick up the rock and assess its weight. If the rock feels lighter than that surrounding rocks, it may be a geode. Geodes have a hollow space inside, which is what allows the crystals to form. You can also shake the rock next to your ear to test whether it is hollow. You may hear small pieces of rock or crystal rattling around inside if it is hollow. Crack open the rock with a hammer. Use a rock hammer or pickax to crack open the suspected geode. Place the rock on the ground and strike it in the center with a hammer to split it into two pieces. While there are clues that can lead you to geodes, the only way to verify whether you've truly found one is to take a look inside. Make sure to wear safety goggles while trying to open the geode. If you do not want to attempt to open the geode yourself, you can also take it to a rock or gem store to have it opened for you. Identify the minerals inside. Use a mineral identification key to determine what kind of mineral your geode contains. Match the descriptions in the key to the appearance of the crystals found inside of your geode in order to properly identify what kind you have unearthed. Mineral keys describe the mineral's habit, which refers to its key characteristics and features. Cut and polish your geode. Use a chisel and hammer to break off pieces of the geode to clean and polish. Use a handheld rotary sander to grind the geodes into shape then rub them with a polishing cloth until you begin to see luster. Polishing your geode will bring out the most in its beauty. You can also coat your geode with mineral oil to increase its luster. 
Consult a geode map. Survey your surroundings for likely geode locations. Verify whether you are on private property. Look for round rocks. Check the surface for bumps. Test whether the rock has a hollow interior. Crack open the rock with a hammer. Identify the minerals inside. Cut and polish your geode. 