pictures that help.

But identification is best made by noting the physical characteristics
of the rock or mineral. For minerals, there's a hardness scale in
which a mineral of the higher number can scratch a mineral of the
lower number but not be scratched by it. The scale is: 1) talc;
2)gypsum; 3) calcite; 4) fluorite; 5) apatite; 6) orthoclase;
7) quartz; 8) topaz; 9) corundum; 10) diamond. Remember it by
this silly sentence: "The girls can flirt and other queer things
can do."

When on a trip, remember that a fingernail has a hardness of 2.5;
a penny, 3; a knife blade, 5.5; and a steel file, 6.5. Use these
to scratch your sample and you can get an approximate idea of its
hardness.

You can buy a set of hardness points. They're pointed pieces of
minerals set in brass tubes, each marked with its hardness scale.
The set costs about $30 (half that if you assemble your own).

Other tests for identifying minerals include specific gravity
(weight of mineral compared to the weight of an equal volume of
water), optical properties and crystal form, color and luster.
Minerals differ in cleavage and fracture (how they come apart
when cut). They leave distinctive streaks on unglazed porcelain.
Some are magnetic, some have electrical properties, some glow under
ultraviolet or black light, some are radioactive, some fuse under
a low flame while others are unaffected. Many studies with the
dissolved mineral can identify it beyond doubt.