Rocks Rock!

Posted by Alexandra Matiella Novak Dec 8, 2008

The USGS has a great webpage called "Collecting Rocks" that can guide you on how to start or expand a rock collection. Most people don't even pay attention to rocks as they walk by or over them; but knowing what kind of rocks are around you can give you a lot of information about past or present geological processes that have taken place near your home.

I recently wrote an article titled, "How to Identify Rocks". In this article, I explain the main differences between the three types of rocks - igneous, sedimentary and metamorphic. This article is far from complete when it comes to being able to identify rocks in the field. One of the biggest challenges is that you can hardly be prepared to just go out in the field and start naming rocks. It's much easier said then done, mainly because there can be dozens of variations and descriptions for any one kind of rock.

Your greatest chance of success is to already know what kind of rocks are supposed to be in your area. This can be achieved easily by contacting your local geologist and just asking that question: "What kinds of rocks are in our area?" You'll find that most geologists will be more than happy to answer that simple - at least simple to them - question. Take notes - the names will be unfamiliar to you and you may forget them if you don't write them down.

Once you know what you are looking for, the next step is to buy a rock guide or reference book, easily found in your neighborhood bookstore or library. This will give you a clue as to what the rock is supposed to look like.

The next thing you need to do is get the right tools - a rock hammer and a rock lense (or a magnifying glass). Rock hammers are necessary to hammer out chunks of rock with fresh surfaces. Weathered surfaces can be misleading and you can't see the full brilliance of the minerals you are looking for. A rock lens will help you see small minerals or grains clearly.

If you are lucky and live in a geologically interesting area, such as an area where there is a fault that causes two different rock types to meet at the surface, you may find a fun variety of rocks in a small area. A jackpot location for rock hounds is an area where glaciers have been. Glaciers transport and deposit rocks from all around the hemisphere.

One very important thing to mention: You are not allowed to take rocks out of National Parks. If you are on private land, make sure you have permission before you take rocks home with you.