Agate Month

Moss Agate

The name moss agate is a bit of a misnomer, because they contain no moss. Moss agates have green inclusions that look like moss or seaweed. The green color comes from manganese oxide or other green minerals. It is the most common type of agate inclusion. Moss agates are most commonly found in Montana and Wyoming.  The one pictured is from Maury Mountain, Oregon.
Source: The Gemrock (IGAMS newsletter), 7/2014

Crazy Lace Agate

Today’s agate is the Crazy Lace Agate. The complicated layers look like lace, hence the name. Since they are found in Mexico, sometimes they are called Mexican agates. It is not known exactly how they form, but perhaps they were disturbed somehow during silicification, creating the crooked layers.  You may recognize this photo if you visit our Google+ page; it’s one of my favorite mineral photos.

Banded Agates

Agates are a variegated type of chalcedony (a type of quartz) that are made of microcrystalline silicon dioxide crystals formed in distinct bands. The name comes from the Achetes River in Sicily, where agates were first found. Agates are often cut into slabs, or agate pebbles are polished in rock tumblers or made into pretty striped beads. Being a semi-precious gemstone, they polish well and can be made into a lot of things.

Five oval-shaped polished tumbled banded agate rocks with differing shades of brown and white stripes.

Banded agate pebbles that have been tumbled. Photo from:

Banded agates are the traditional, “default” type of agate that you always see in museum gift shops or made into coasters and suncatchers. The colored bands are very distinctive. Since agates are porous, it is very easy to dye them, so you will frequently see agates dyed unnatural colors like bright blue, violet, or hot pink. Not that there’s anything wrong with that. Decide for yourself whether you are willing to buy an agate if it has been dyed, and then be aware that the natural colors of agate are black, white, yellow, gray, brown, red, pale blue, and pale pink. One final tip: If you want agate slab coasters, you’ll pay way too much if you buy them from a home decorating store like in the link. Just get some agate slabs at an upcoming gem show and glue some cork on the back.

A set of six circular banded agate coasters, in dark blue, purple, hot pink, orange, light blue, and brown.  The concentric circles formed by the bands are very pretty.

Banded agates that have been made into cute coasters.  The orange one and the brown one could be natural but the others are definitely dyed. Photo from: