Name _

Date

SCRATCH·TEST MINERALS• • • • •• • • • • • • • • • • • • • • • • • • • • • • • • • • ••• • • • • • •

PROPERTIES

MINERAL 1

MINERAL 3

FOSS Solid Earth Module© The Regents of the University of CaliforniaCan be duplicated for classroom or workshop use.

MINERAL 2

MINERAL 4

229 Investigation 2: Scratch TestNo.7-Science Notebook

SCRATCH-TEST MINERALS•• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •

PROPERTIES

MINERAL 1

Sample answers may include:

white or clear

shiny surface

smooth in some places; rough in

others

MINERAL 3

Sample answers may include:

white, pinkish, brown areas

crumbly or soft

rough surface

FOSS Solid Earth Module© The Regents of the University of CaliforniaCan be duplicated for classroom or workshop use.

MINERAL 2

Sample answers may include:

white or clear

shiny surface

smooth in some places; rough in

others

MINERAL 4

311

Sample answers may include:

white, purple, blue, green,

yellow

shiny surfaces

smooth in some places; rough

in others

Investigation 2: Scratch TestNo.7-Science Notebook

Hardness

What Would You Like to Know?

-What is Hardness?The hardness of a mineral is its ability to resist scratching.

-Where did the hardness scale originate?Friedrich Mohs, a German mineralogist, developed a hardness scale over 100 years ago. The hardestmineral known, diamond, was assigned the number 10.

-How does the hardness scale work?

The Mohs Hardness Scale ranks the order of the hardness of minerals. Different objects are used toscratch the surface of the mineral to determine how hard it is. The minerals are then placed on a scaleof 1-10, from softest to hardest. Minerals rated 1, are the softest and minerals rated 10, are the hardest.

The common objects used to scratch minerals are, a fingernail, aluminum nail, and a steel paperclip.The object used to scratch the mineral with MUST be harder than the mineral or it will not leave ascratch. A fingernail is the softest object suggested for doing a scratch-test on a mineral.

Here is an example, your fingernail can scratch the minerals talc and gypsum, with a hardness of 2 orlower. An aluminum nail can scratch calcite, gypsum, and talc because it is harder than those minerals.An aluminum nail will not scratch a mineral that is rated harder than a 4, like Orthoclase, which is rated6 on the hardness scale. To be able to scratch quartz, you need something harder than an aluminum nail.A steel paperclip is harder than an aluminum nail, therefore, it will scratch quartz.

- Where do gemstones rank on the hardness scale?

Minerals and gemstones are both found in the Earth's layers. They are both ranked on the MohsHardness Scale. Minerals are softer than gemstones. Gemstones are rated on the harder end of thehardness scale. Any mineral rated 1-6 are considered just minerals, and those rated 7 and up areconsidered gemstones. Diamonds are the hardest gemstone and are rated at lOon the hardness scale.Just like with minerals, gemstones such as ,diamonds, can also be different colors.

Mobs Hardness Scale

1- Softest10- Hardest

BARDNESS SCALE INDEX MINERAL COMMON OBJEC,.S

1 Talc

2 Gypsum Fingernail

3 Calcite

4 Fluorite Aluminum nail

5 Apatite

6 Orthoclase

Gemstones

7 Quartz Steel paperclip

8 Topaz

9 Corundum

10 Diamond glass

Adapted from Mineralogy 4 Kids: Mineral Identification