Laura Rogers, age 15, of Pocatello, Idaho, for her question:

WHERE CAN YOU FIND TOPAZ?

Topaz is a hard, transparent mineral. Gem topaz is valuable. This precious stone can range in color from rich yellow to light brown or pinkish red. It is one of the hardest of gem minerals.

Topaz is found in many parts of the world, but especially in Brazil, in the Ural Mountains of Russia and in the United States. Most of 'the finest precious topaz comes from Brazil.

Blue topaz is often sold as aquamarine, and a variety of brown quartz is widely sold as topaz. This quartz is much softer, less brilliant and more plentiful than true topaz.

Most of the world's topaz is white or blue. The white and blue crystals of topaz are large, often weighing thousands of carats. For this reason, the value of blue topaz does not depend so much on its size as it does with diamonds and many other precious stones, where the value increases about four times with each doubling of weight. The quality of topaz largely determines its value.