Question

mohs hardness scale
increasing hardness
mineral name scale number common object
diamond 10
corundum 9
topaz 8
quartz 7
orthoclase 6
apatite 5
fluorite 4
calcite 3
gypsum 2
talc 1
if an unknown mineral can scratch a penny but cannot scratch an iron nail, what is its approximate hardness?
between 3.5 and 6.5
between 1 and 2.5
between 6.5 and 8
between 2.5 and 3.5

Explanation:

Step1: Identify penny's hardness

From the Mohs Hardness Scale, a copper penny has a hardness of 3.5.

Step2: Identify iron - nail's hardness

An iron nail has a hardness of 6.5.

Step3: Determine unknown mineral's hardness range

Since the unknown mineral can scratch a penny (hardness 3.5) but not an iron - nail (hardness 6.5), its hardness is between 3.5 and 6.5.

Answer:

Between 3.5 and 6.5