Beach stones identification is more a matter of knowledge and experience than skill. If you want to be able to identify pebbles, you should remember the following:
Pebbles are like all other rocks and minerals. For beach stones identification you first need to acquire knowledge about rock formation and minerals. Buy books and guides about minerals, take a course for rock-hounds, search online sources, become a member of an online rock-hound group, look at a lot of pictures of rocks and minerals, visit rock and mineral museums, go to gem shows, study geological formations in the area that interests you. All this information helps identifying rocks whether on the beach or elsewehere. You will need some basic tools (easy to find, not expensive ones) to help you with identifying rocks. These tools are: a special heavy hammer for rockhounds, a porcelain tile, a coin, a piece of glass, a steel nail, a magnet, a magnifying glass, protective goggles, Mineral Guide-Book, Rock Id Tables (or Mineral Keys). If you don’t know the geology of the place well you should also carry a quality radiation detector for radioactive rocks (there are pocket size ones in the market). Use it to test the rocks you approach and the ones that interest you.
Below are some easy to follow steps for beach stones identification (Remember that Kids should ALWAYS be attended by an adult!):
1. To identify pebbles and beach stones you should first wet the stone or pebble, so you can have a good look at its colors and get a first idea of how the rock was formed and what mineral or minerals it could be composed of. Some rock types are very distinctive, like volcanic breccia (as the rounded pebble in the picture), and you could often tell some minerals from their color, like amethyst (a light or dark purple gemstone).
2. Examine your beach stone’s surface. Is it waxy, glassy, sub-metallic? Use your magent to see if it’s magnetic. Chalkedony is waxy, Obsidian is glassy, Hematite is sub-metallic. The problem with pebbles and beach stones is that the weathered rock’s surface doesn’t help. So, if you really want an identification for your pebble you either ask some spencialist to do it for you or you have to use your heavy hammer and break the stone to see its luster. (BE VERY CAREFUL : When breaking stones with a hammer you MUST protect your eyes with special protective goggles for rockhounds. Some rocks are very difficult to break. NEVER keep kids unprotected close to you while breaking rocks and NEVER let them break rocks on their own unprotected and unattended.) After you’ve broken the stone and have narrowed your beach stone's identification search further you can continue with the next step.
3. As you can see the mineral structure of your pebble stone now that it is broken, pay attention to what kind of crystal shapes have grown. Are they like fine needles, cubic, prismatic, tabular, like pyramids? If you can’t see them well with naked eye, it’s time to use your magnifier. Then go to the Rock Guide and your Rock Key to narrow down your pebble stone’s identity search once more. So now you are ready to move on to step 4.
4. Look at your broken pebble carefully. Is the broken surface regular, does it have sharp and scratchy points, is it rough, smooth, splintery? After you’ve decided what it looks like go back to your Rock Guide and Rock Key again and narrow your search according to fracture and cleavage. Then continue with step 5.
5. Now take out your porcelain tile and turn it over, to use the unglazed side. Drag your beach stone along the tile’s surface, putting some pressure on the stone so that it leaves a line on the tile - it’s called a mineral streak test. The color of the line tells you a lot about the kind of mineral you have in your hand. Go to your rock identification table for further information.
6. Finally, you need the coin, the steel nail and the piece of glass to test the stone’s hardness. But first try to scratch the smooth surface of your pebble with your finger-nail. If there is no sign of scratching left on the stone, try to do the same with the coin. A copper coin has a hardness of 3.5 on the Mohs Scale. If there is no mark left, try the piece of glass. Glass has a hardness of 5.5 on the Mohs Scale. If you still see no mark left on the pebble, use your steel nail to scratch it (hardness 7.5). If not even this leaves any scratch then you know that your pebble-rock is harder than 7.5 on the Mohs Scale. So, to identify your stone go to your Mineral Key and look for minerals that are of a hardness from 8+.
If you need more information and some tables and keys for identifying rocks go to the following RESOURCE:
Geology Info and Identifying Rocks help from About.com