What Is A Geode Rock

The only true way to know if a rock is a geode is to crack or cut it open and find out if it contains a crystal core.

What is a geode rock.

In ohio a large geode called crystal cave is open for tours. Iowa a state known for its geode deposits has the geode as its state rock officially designated in 1967 and has a state park called geode state park. These rocks may range in size from a few centimeters to several meters in diameter and they come in many different shapes including spheres ovals oblong blobs and irregular masses. From the outside a geode looks like an ordinary rock.

Geodes derived from the greek word γεώδης meaning earth like are geological secondary formations within sedimentary and volcanic rocks geodes are hollow vaguely spherical rocks in which masses of mineral matter which may include crystals are secluded. Shells tree branches roots and other organic materials often decay away to leave a void for the formation of mineral materials. Geo means earth and these amazing rocks. Except for being kind of roundish there isn t much remarkable or interesting about them.

This celebration of geodes does not stop with iowa. The crystals are formed by the filling of vesicles in volcanic and sub volcanic rocks by minerals deposited from hydrothermal. From the exterior a geode appears to be a boring round shaped rock with little to capture one s attention. The only difference between a geode and a nodule is that a geode has a hollow cavity and a nodule is solid.

Geodes are like the tootsie roll pop of the geology world because underneath the hard exterior lies a surprise center. Geodes in sedimentary rocks are usually found in limestones dolomites and calcareous shale in these deposits a gas filled void can serve as the opening for geode formation. A geode is a rock with a special surprise inside. What you want to do is check the weight.

Rocks which are completely filled with small compact crystal formations such as agate jasper or chalcedony are called nodules. Some geode rocks are the size of a pea others are the size of a soccer ball or even larger. Geodes can also be embedded inside another rock layer such as limestone. The term geode is derived from the greek word for earthlike and refers to a hollow rock with a crystal lined cavity.

If a rock like this is broken open however it will reveal a center that is filled with colorful crystals. This can make geodes hard to precisely identify as whole rocks for the beginner.