Oolite

Oolite is a variety of quartz which occurs in minute spherules. It is solid brown in color, and is very similar to wave-patterned algae. At one sixteenth of an inch (one to two millimeters) the oolite spherules are too small to be cut and are usually just polished to bring out the color and mounted in silver jewelry (particularly tiaras or pectorals). A typical specimen has a base value of 10gp.