How To Start a Rock Collection

Collecting rocks is the perfect hobby. You can find rocks almost anywhere, they are free, and each one is much older than anything you will ever find in an antique store. The specimens you collect can be proudly displayed in your home, hidden away in plastic bags and shoe boxes, or put to work as paperweights, door stops, bookends, and garden borders. Some rocks have exciting stories to tell about volcanic eruptions, epic floods, meteorite impacts, earthquakes, and advancing glaciers. Others speak to us about the lives of animals and about oceans, mountain ranges, and other environments that no longer exist. Deciphering these stories is the real value of the hobby. With a few simple tools and resources, you can begin collecting and identifying rocks and in doing so learn a lot about the natural history of the places you live, work, play, and travel to.

1. Educate yourself. Visit your local library and pick up some books or go online and browse any number of excellent web sites that provide basic earth science information. Make sure that you know the difference between igneous, metamorphic, and sedimentary rocks and the major subdivisions of each of these rock types. Learn about differences in rock composition (what minerals are in a rock) and texture (grain size, layering, etc.) and what these can tell you about the environment a rock formed in, how quickly it cooled, or what pressures or temperatures the rock has been subjected to. A basic understanding of plate tectonics and depositional environments (the places that sediment, which later becomes sedimentary rock, can end up) will help a lot. If you decide you really like this hobby, you can learn even more by taking a class at your community college.
2. Get a rock identification guide. Visit your local library, or go online to find one or more rock identification guides. Stay away from books that are simply pictures of museum quality specimens. These are nice to look at, but probably won't be too helpful. Find resources that are well illustrated and provide a straightforward process to identify common rock types. Try any reference out for a period of time before buying a personal copy.
3. Find out what types of rocks exist in your area. Visit your state or regional geological survey in person or online. The American Association of State Geologists website provides links to surveys in each U.S. State. Request materials or publications that discuss rock types and geologic history in your area. If a geologic map is available, get a copy. Ask to speak with a geologist who is familiar with your area. They will be happy to fill you in on what to expect to find while collecting. Many college geology departments also have regional and educational information on their websites. In addition, some areas have an independent geological society that conducts field trips each year. These trips are usually open to everyone and provide excellent opportunities for collecting and "free" training from professional geologists.
4. Learn collecting rules in your area. There are usually no restrictions on hobby rock collecting on private property if you have permission from the property owner. Collecting is also typically allowed on U.S. National Forest and Bureau of Land Management property, but is rarely allowed in U.S. National Parks or Monuments or in state and local parks. If you are unsure, always check first.
5. Assemble a tool kit. A rock hammer comes in handy. It is used to break a piece of rock from an outcrop or make a larger rock sample smaller. If you are in an area which has primarily sedimentary rocks, a hammer with a flat chisel end will work well. You can usually pick up a hammer like this at a home improvement store. It may be called a masonry hammer.

   Hammers with a pick point are most common among geologists, but usually need to be ordered from a specialty store. If you are in an area with harder igneous and metamorphic rocks, or are working with larger rock samples, a sledge hammer will be a useful addition to your tool box. A chisel is also a good investment.

   Always use eye protection when hitting rocks or chisels. Long pants, shirt sleeves, and gloves are also a good idea. Other basic tools that may be useful include:

   • A shovel
   • A hand lens or magnifying glass for looking at minerals in finer grained rocks
   • A bucket and some stiff bristle brushes for cleaning off dirty samples
   • Plastic or paper bags for storing samples
   • Dilute (10%) hydrochloric acid is helpful for differentiating between limestone and other rock types, if limestone is present in your area. If you are able to work safely with chemicals, you can make your own supply by diluting muriatic acid that is available at your local hardware store with water. Always store acid in a thick plastic bottle made for the purpose and avoid contact with skin and clothing.
6. Get started. Start collecting close to home. If you have rocks on your property, find an example of each type that is present and try to identify it. Next, look for rocks at places you visit frequently and ask permission to collect samples. Gravel driveways and parking lots are good places to see what local rock types are available. If your area is rock poor, you can visit downtown buildings, local monuments, cemeteries, landscaping centers, and home improvement stores to see or purchase a wide range or rock materials.
7. Expand your collection. At some point, you will begin to have difficulty finding new rock types in your local area. You can continue to expand your collection by bringing back rocks from business trips and vacations, asking relatives and friends to bring you interesting rocks they find on their journeys, and visiting gem and mineral shows. Many areas also have mineral clubs, which have periodic collecting trips to quarries and other difficult to access locations. Club members may also be interested in trading or giving away samples.
8. Share your knowledge. If you assemble an outstanding collection of rocks in your area, take it with you and visit local school groups, scouting groups, and retirement home residents, or offer to display it at your local library.