There are two basic types of geode.
Round rocks with crystals inside.
Shells tree branches roots and other organic materials often decay away to leave a void for the formation of mineral materials.
How do you get a hollow rock with lots of sparkling crystals inside.
Test whether the rock has a hollow interior.
The crystals are formed by the filling of vesicles in volcanic and sub volcanic rocks by minerals deposited from hydrothermal.
I bought these rocks from a small etsy shop they claim to have crystals inside when you smash them open.
Hollow rocks so let s start at the beginning.
Most geodes are approximately the size of a basketball.
Sedimentary rocks such as limestone or shale are hardened sediment with sandy or clay like layers strata they are usually brown to gray in color and may have fossils and water or wind marks.
A geode is a round rock which contains a hollow cavity lined with crystals.
Igneous rocks such as granite or lava are tough frozen melts with little texture or layering rocks like these contain mostly black white and or gray minerals.
Many excellent books and websites have been written to help identify crystals on or within rocks.
How are geodes created.
They can range from the size of a nut to several feet.
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.
Collect several rock samples with crystals before identifying them.
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.
Geodes with volcanic.
Geodes start their lives as a hollow bubble inside a layer of rock.
When broken or cut open geodes reveal a lining of crystals or other materials inside.
Crystals with small flat surfaces are said to have facets all crystals have a faceted surface but not all crystals have multiple facets.
Geodes are generally round though some are egg shaped.
The only difference between a geode and a nodule is that a geode has a hollow cavity and a nodule is solid.
Geodes have a hollow space inside which is what allows the crystals to form.
Those formed from volcanic rock and those formed from sedimentary rock.
You can also shake the rock next to your ear to test whether it is hollow.
Pick up the rock and assess its weight.
If the rock feels lighter than that surrounding rocks it may be a geode.
