Q&A for How to Crack Open a Geode

It is not recommended to use a sledgehammer as it will smash the geode into many pieces and can destroy the crystals/formations inside. Hammer and chisel is a much better method.

Over many years, mineral water seeps into the rock. As the water makes its way through the rock, the minerals get sifted out, and are left behind in the rock in a crystalline formation according to the type of minerals in the water.

No, but the method provides a good measure of safety by preventing the pieces from flying all over the place.

No, geodes can come in a variety of shapes. Some may be round, oblong, conical or any other shape. However, most geodes are round or have rounded edges.

If you like them, keep them! If not, ask other collectors if they'd like them.

Geodes come in different colors. I've found rubies in some, which are red, and amethyst and others which are purple.

There are many different types of crystals in geodes, like quartz crystals, purple amethyst crystals, agate, chalcedony, or minerals like dolomite.

It depends on the method you are using. I would say the diamond blade saw method would be the safest bet. You can saw it right down the middle without splitting it into several different parts.

It depends on where you live, but at least around Indiana and Illinois they are roughly 300 Million years old. Geodes began as chunks of anhydrite (CaSO4*0H2O) on the floor of an ancient sea, but over time they were buried and dissolved by mineral-rich water, leaving behind a hardened rind (typically chalcedony) filled with crystals of whatever substances the groundwater contained.

A geode will not open on its own.

It depends on if it is a hollow geode or a solid thunderegg. A hollow geode is not always evenly coated on the inside while a thunderegg is solid, so it would be my opinion that you would waste a lot of geodes trying this.

Geodes are usually spherical shaped and are probably not going to be a random rock you pick up off the street. I found about a dozen in a creek next to the Mississippi River. They don't look like other stones in a river, which are really smooth and thin. Geodes are very round, with usually hardly any straight sides, and are also known to be light for their size. They are also rather bumpy or "hilly".

On the outside, they look like plain, rough stones. But when you break them open, you can see concentric bands of color surrounding a hollow interior. Oftentimes, that interior is packed with miniature crystals. You can do an image search to see pictures.

Yes, but you should be very careful.

Diamonds need a lot of heat and pressure to form. Due to the nature of how geodes are formed, this is not possible.

Yes, place it near a fire until warm to the touch, them use one of the methods above.

No, it doesn't make a mark. Try some of the methods and you might have some luck.

Theoretically, yes, but I wouldn't recommend that because you might drill into the crystals inside, ultimately damaging them.

On the outside, they look like plain, rough stones. But when you break them open, you can see concentric bands of color surrounding a hollow interior. Oftentimes, that interior is packed with miniature crystals. You can do an image search to see pictures.

Place the geode in a sock and swing it at a hard surface such as the asphalt, rather than hitting it with a hammer. This method still breaks the geode into many pieces, but it could damage the asphalt.

It depends on the number of minutes the timer is set for and how hard it is on the inside.

I have found many geodes in Brown and Monroe counties. Check creek banks and road construction sites.

You could use the sock method and bang it on a solid surface outdoors so it will break open, but it will be more vulnerable to damage and will break into little pieces. Don't use this method if you are looking for a two-piece split.

You can try to strike it with another, large rock. Be warned that this could cause it to shatter into differently size pieces.

This grinder with a diamond blade will cut slices in geodes with ease, and by changing the disc, you can also sand and then polish the slices. If you only use an ordinary angle grinder, however, you can keep the surface of the mineral or rock wet with mineral oil to prevent the rock from overheating or cracking.

No. There is no simple way to tell what's inside a geode without opening it up to see.