Streak tests are where you scrape off a piece of the rock onto a streak plate to see the color.  Streak plates are porcelain plates a few inches across.  You do a streak test because the actual rock can vary in color.  Calcite can be any color of the rainbow, but always has a white streak.

Hardness test is an easy way of testing minerals.  The standard scale is Mohs’ Hardness Scale 

1 = Talc

2 = Gypsum

3 = Calcite

4 = Fluorite

5 = Apatite (fluorapatite)

6 = Orthoclase

7 = Quartz

8 = Topaz

9 = Corundum

10 = Diamond

A more interesting scale is the following: 

your fingernail has a hardness of 2.5,

a penny has a hardness of about 3.5,

glass and a steel nail have nearly equal hardnesses of 5.5 and

a streak plate has a hardness of 6.5.

If you get a nail, a streak plate, and a penny, you can easily test minerals of between 2.5 and 6.5.

Photograph by Lori Miller

Testing Fun:  Scrape a rock with a penny. Does the rock scrape off onto the penny? Does that mean it's harder or softer than the penny? Scrape it against a nail. What happens this time? Scrape a piece of chalk against a penny. What happens? Why does this happen?