Beach Rocks

Agate

Agate is a form of microcrystalline quartz, very hard and usually banded. Chalcedony is a name for very similar unbanded rocks, and jasper is used to name similar rocks that are red-brown and featureless. Agates for in lava flow tops and can be found on most Keweenaw beaches, although they are prized and captured by roving humans.

Links:

agates: how they form

agate basics:

agate, jasper, chalcedony

Lake Superior Agate