Calculate the density of a rock composed of the four minerals listed below (toge

Question

Calculate the density of a rock composed of the four minerals listed below (together with their abundances and densities):

Mineral Abundance by volume %      Density g/cm^3

Olivine- 10                                                      3.30

Augite- 45                                                    3.20

Plagoicloase 30                                              2.68

Magnetite 15                                                  5.18

Hint: The total mass of the rock is the sum of the masses of its minerals.How does this compare with the Earth’s average density and what does this therefore indicate about the composition of the Earth in terms of the minerals listed here?

Explanation / Answer

Minerals are the building blocks of the rocks, so in order to determine the density of the rock we need to sumup the mineral abundance density to determine the density of the rock, here I am using Dr for the rock density

Dr = (10% of 3.30 +45% of 3.20 + 30% of 2.68 +15% of 5.18)/100%

=(0.33+1.44+0.804+0.777) = 3.351g/cm3 .

So the rock is having an density of 3.351 g/cm3 .

Well when we compare with the earth average density which is 5.513 g/cm3. which is very high when compair to that of the given rock density which is only 3.351 g/cm3.

When we look at the elemental abundance of various element we find that O, is the most abundant element on the earth followed by Si, Al, Fe and so on. Hence it's very clear that earth will be consisting mainly by the silicate groups of minerals which are more abundant in nature.

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.