Lab#11 Part 1: Identifying Minerals
Minerals are defined as naturally occurring, inorganic, solids with a definite chemical composition and a
regular crystalline structure. The keys to this definition are the chemical composition and the crystalline
structure. Different chemical compositions result in different minerals. A good example is the mineral
plagioclase. There is more than one type of plagioclase Albite and Anorthite. Albite has a chemical composition
of NaAlSi3O8, while Anorthite's chemical composition is CaAl2Si2O8. Very similar, but different - therefore
two different minerals.
Different crystalline structures, or how the atoms and molecules are arranged, result in different
minerals. A good example is diamond and graphite. Both minerals are composed of carbon (C). They have the
same chemical composition, but two different crystalline structures - therefore, two different minerals.
Determination of the actual chemical composition and crystalline structure of a mineral is difficult
without the proper equipment. Fortunately, these two aspects also determine a mineral's physical properties.
While many minerals share common physical properties, when all of a mineral's physical properties are
examined, it often results in a unique set of physical properties, which can be used to identify the mineral.
Procedure:
1. Go to http://facweb.bhc.edu/academics/science/harwoodr/Geol101/Labs/Minerals/
TYPE IT EXACTLY AS WRITTEN or search Mineral ID Lab
2. Scroll to the bottom of the page until you see:
•
Select a Sample to Identify:
1 •2 •3 •4 •5 •6 •7 •8 •9 •10
11 •12 •13 •14 •15 •16 •17 •18 •19 •20
3. Select mineral #3. You will see an image of the mineral to identify. Scroll down and you will see
“Physical Properties Testing” buttons, Mineral Identification Worksheet, and mineral names.
4. From the image fill in color, luster and crystal form on the computer AND on your record sheet.
5. Click the Hardness button #1. Continue clicking the #’s until the mineral was scratched. Fill in the
highest NOT scratched # as the hardness on the computer AND on your record sheet.
6. Click the Cleavage Button. The results will provide the answer to Cleavage, Fracture and Crystal
form. Fill in the answer on the computer AND your record sheet.
7. Click the Streak Button. Fill in the answer on the computer AND your record sheet.
8. Click the Magnet, Hydrochloric acid and taste button, one at a time. If there is an answer record
them in other on the computer AND on your record sheet. If there is no results for either 3 then fill
in N/A.
9. Using the mineral physical property chart, match the properties to the name of the element.
10. Fill in the name on the computer and click grade identification. It will say congratulations if you
have identified it correctly. If not it will instruct you which parts(s) were wrong for you to correct
or re guess and answer. Record the correct name on your record sheet.
11. Repeat steps 3-10 for samples 5,9,11,14,16,17 & 20.
Conclusions:
1. Is Albite and Anorthite a silicate or a Non- silicate mineral? Explain?
2. Suppose you find a mineral crystal that is as tall as you are. What kinds of factors would cause such a
crystal to form?
3. Describe what each of the following pairs have in common:
a) Sulfates and Sulfides b) Sulfates and Oxides c) Silicates and Sulfides