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Gold Rush Adventure Game

Lesson #1 The Scratch Test

Follow these simple steps to get started working on your first million....pieces of gravel?

To experience the tests involved with mining techniques; two techniques are for hardness and lustre. After the outdoors experience, have the class reflect on various Prescribed Learning Outcomes

Gold is a mineral A mineral is a naturally occurring substance which has a unique molecular structure and physical characteristics. Gold miners use a set of simple teststo test these characteristics and to identify the different minerals. Here are some easy ones to try out - get some minerals and see if you can figure out what they are.

The Scratch Test: Moh's Scale

Mineral hardness is determined by a relative scale called the Moh's Scale.

It is relative because ten minerals - chosen from the softest to the hardest - are used to compare or relate each other to.

To perform this test, see if one of the the items listed in brackets can scratch the mineral (the item should be able to scratch the mineral it's beside and everything with a lower hardness.)

  1. Talc (softest ... pencil lead)
  2. Gypsum (your fingernail)
  3. Calcite
  4. Fluorite (a copper penny ... look for oldpennies!)
  5. Apatite (a knife blade or window glass)
  6. Feldspar (a steel file)
  7. Quartz
  8. Topaz
  9. Sapphire
  10. Diamond (hardest ... this scratches everything!)

Gold has a hardness of 2.5 to 3 on the Moh's Scale.

The Luster Test

The luster test is used to describe the way the mineral's surface reflects light. There are two general categories: metallic and non-metallic. Luster can vary within a sample of mineral or change depending on your angle of view. Here are the categories for non-metallic lusters (metallic lusters are just classified as "metallic"):

the luster of glass (e.g. quartz)
the luster of resin (e.g. amber)
as if covered with a layer of grease or oil (e.g. serpentine, some quartz)
the iridescent sheen of mother-of pearl (e.g. talc, mica)
the lustrous, fibrous sheen of rayon or silk (e.g. fibrous gypsum, asbestos)
the hard, brilliant flash of a diamond (e.g. diamond, corundum - that's the mineral which makes up rubies and sapphires)
a surface showing little reflectivity (leucite)
the powdery, crumbly look of compacted soil (kaolin clay)

Gold has metallic luster.

Last updated November 30, 1998.
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