State and national parks have bans on "collecting," and this technically includes agates and other stones that are often found in the surf zone. Individual parks and park districts are usually given much leeway in enforcing these regulations, however, and most of them exempt the casual gathering of semi-precious stones for personal use.

It's almost always OK to collect driftwood in reasonable quantities, but beachcombers should check park brochures or speak with the rangers if they have any doubts.

When poking around in tide pools, coastal campers should be sure to leave all marine creatures where they were found and replace any overturned rocks. It's OK to take certain inter-tidal critters in some areas, but strict regulations apply, and you need a fishing license to do so.

Collectable stones are usually found in pebbly shoals on an outgoing tide. Unfortunately, they're much prettier when wet. To give them a temporary shine, put a tiny drop of cooking oil on the palm of your hand and rub it into the stone.

What follows are some of the most common collectible rocks found on West Coast beaches, particularly those to the north.

Agate: A translucent, quartz-like stone with marbled stripes or clear, crystalline bubbles. Agates have a pleasingly smooth feel and can be almost any color. They develop when minerals form pockets within softer, volcanic stone.

Moonstone: An opalescent, semi-precious member of the feldspar family that's typically translucent or bluish in color (the bluer the rarer). Disks of white agate or white quartz are often mistaken for these beauties. Only a few California beaches will have them. The name "Moonstone Beach" is a not-so-subtle clue that you've come to the right place.

Jade: Any place you find outcrops of a green, oily-feeling mystery stone called serpentine, you'll probably find jade. This includes most of the North Coast and some portions of the Big Sur coast. When the surrounding serpentine wears away--typically through wave or stream action--smooth lumps of jade are left to wash up along the coast. These greenish or occasionally blackish stones are much harder and heavier than green chert, for which they're often mistaken.

Carnelians: This small, brightly-colored semi-precious stone emerges when a mineral called orange chalcedony is weathered by waves. Gravel-sized pieces are found on chert-sand beaches like those on the western side of the Marin Headlands.

Chert: This is the most common "pretty rock" you'll find on California beaches. A sedimentary silica, it comes in various shades of green, brown, red, pink, black, gray, or orange. California Indians made their projectile points out of it because it chips into sharp, uniform shapes that take a good edge.

Jasper: This heavy, fine-grained quartz is usually a wild mixture of reds, yellows, and browns. Definitely one of the more pleasing rocks to look at.