Madeline Weisberger, age 13, of Highland Park , for her  question;

What is the scale of hardness for stones?

Your first rock collection may be just a passing fad, but it is not a waste of time. You will discover the glamour of everyday stones and they never again will seem drab. On the other hand, your first collection may lead to a fascinating life long hobby or oven to a rewarding career,

You can gather a wide assortment of stones on a few trips to the fields, the hills or the beaches. When the specimens are classified and labeled you have a rock collection and this is a stepping stone into the science of geology. In a science, words have exact meanings. Rocks and stones are made from minerals and minerals are the non living chemicals from which our planet is made. A rock hound refers to his specimens as minerals .

You can make a wick guess about a mineral from its color and texture. Let’s say you have a sample of quartz and one of feldspar. Both could be milky white, but the one with the smoother surface is more likely to be quartz. The mineral hardness test can toll you for sure. When you rub the two specimens together, the quarts will leave scratches on the feldspar   but the feldspar cannot scratch back. Quartz is harder than feldspar.

There are ten classes in the mineral scale of hardness. The minerals in classes one and two are soft enough to be scratched by your finger nail. You need a copper penny to scratch the harder minerals 3n class three and a. knife blade to scratch classes four and five. The diamond in class ten is the hardest natural mineral it can stretch other minerals and none of them can scratch it back.

Quartz is in class seven of the hardness scalp and feldspar in class six. You can memorize the ten classes with one of Andy’s easy learn tricks. List the first letter from each word in the following sentence, The gull can fly and float quietly for several days. The letters stand for the minerals talc, gypsum, calcite, flourite, apatite, feldspar, quartz, topaz, sapphire and diamond. The list ranges from ciass one, the softest, to class ten, the hardest of the minerals. The diamond is in a class by itself, but there are many minerals in each of the other classes. Many other minerals fall between the definite classes. Silver rates 2.5 and uranium rates 5.5 on the mineral scale of hardness.

You will need a guide book to help you classify your collection and the simple hardness test will tempt you to try more elaborate tests. You will want to discover the specific gravity, the cleavage and the chemical reactions of your specimens. When you use ultraviolet or fluorescent light tests many of your drabbest specimens will glow with jewel colors.

The Mohs scale lists the hardness of minerals as follows, starting  with the softest as number  1:

1. Talc 2. Gypsum  3.Calcite  4.Flourite 5. Apatite  6.Orthoclase 7.Quartz  8.Topaz 9.Corundum  10. Diamond