Igneous rock may form crystalline structures as it cools giving it a granular appearance.
Rocks with white crystals inside.
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.
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.
Igneous rock is created by volcanic activity forming from magma and lava as they cool and harden.
Finding a cool looking rock and then dissolving the calcite out of it with white vinegar to expose crystals in one week.
Typically the inclusion of clay gives jasper a yellowish white to gray tone.
It is most often black gray or white and often has a baked appearance.
If no crystals form the result will be natural glass.
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.
Dalmatian jasper a fine grained dense quartz called chalcedony jasper is found in a variety of colors.
Collect several rock samples with crystals before identifying them.