Agate is a semi-precious gemstone valued by collectors for its rich colors, banding patterns and reflective qualities. This hard rock forms when liquid quartz fills an empty pocket inside another rock, usually lava. No two agates are exactly alike. Colors and patterns vary according to changes in temperature, mineral content and pressure as agate forms. Agates can be found in many areas of Michigan.
Wear sturdy, comfortable shoes to search for agate. You will be on your feet for a long time walking, climbing, stooping and squatting. Take a backpack to put rocks in.
Search for agate on a sunny day early in the morning or late in the day. The sun's rays that slant across rocks bring out a translucent glow from the quartz that's in agate. Walk into the sun and squat low to the ground. Agates will reflect light more than other rocks.
Look along the shoreline right after a storm when new rocks wash up on the beach. Look into water near the shore in the spring, on ledges, at the edges of inland rivers, in creek beds, along railroad tracks and beside the road, especially in construction areas.
Ask for permission to search in gravel pits, mines and any other private property. Use a flashlight to look for the soft glow of the agate and banding that you can't see without the light. Agate is easier to find in gravel pits following a windstorm.
Find agate in the Lower Peninsula on Lake Michigan and Traverse Bay beaches. Look on the Lake Michigan side of the Leelanau Peninsula and in gravel pits throughout Lower Michigan.
Find agates on Michigan beaches in the Upper Peninsula such as Grand Marais Agate Beach, Santa Monica Beach, Paradise, Whitefish Point, Marquette, Houghton and the Keweenaw Peninsula's Great Sand Bay or Copper Harbor. Get permission to visit one of the copper mines. Visit one of the many rock shops and museums for a class or maps that will lead you to agates in Michigan or take a rock collecting tour.
Look for rocks less than three inches in diameter that are heavier than rocks of the same size. Look for rocks with a pitted surface and a potato skin-like texture, or broken rocks with an almost perfectly smooth natural surface. Search for rust-red or yellow stains, straight parallel bands, round bands called "eyes" and a glossy, waxy look on chipped surfaces. Look through rock piles for gray rocks with a waxy luster. Try to scratch a rock you think is agate with a knife blade. Agate is too hard to scratch.
Buy or check out a library book that helps you identify and find agates in Michigan. Try "Is This an Agate" by Susan Robinson, "Understanding and Finding Agates" by Karen Brzys, or "Lake Michigan Rock Picker's Guide" by Bruce Mueller.
Be aware that there are rocks that resemble agates. These include chert, jasper, flint, fossils and metamorphic rock.