Which property would be most useful for identifying igneous rocks?

Question

A- kind of cement
B- mineral compostition
C- number of minerals present
D- types of fossils present
Pleaase explain why you chose your answer

Answer 1

B Mineral Composition is the correct answer.

I teach high school Earth Science and have a MS in Geology. The way that we make positive identification of igneous rocks was by examining thin sections under a microscope and determining what minerals are present, in what percentages they are present and how large and well formed the crystals are.

A thin section is a slice of rock which is thin enough that light will go through it like any other slide on a microscope. Each different mineral will exhibit its own special properties this way.

Letter C - the number of minerals present would be a partial factor in identifying an igneous rock but B - the types of minerals is much more important and valid.

Answer 2

For an igneous rock, between the main obvious residences are the interlocking crystals, this could each so often be perplexing to work out in a typical hand pattern, yet i'm helpful you have viewed a granite rock earlier, once you look close you will see black specs (biotite, amphiboles) grayish/white crystals (quartz) and darker gray to salmon colored crystals (plagioclase). yet another could be "phenocrysts" that are greater effective than well-known crystals in the rock, in spite of the actuality that they won't look like a "crystal" that's in truth only a miles better mass interior of a rock that exhibits the interlocking crystals (do no longer confuse this with a conglomerate) various different residences are glassy volcanic rocks (obsidian basalt) which has a conchoidal fracture, you additionally could have aphanitic (fantastic grained crystals perplexing to work out without a hand lens) and phaneritic (coarse grained, like the interlocking crystals i discussed above). there are a number of greater yet countless them are only seen with a petrographic microscope, from 40x magnification to 400x, yet you could only see those in skinny sliced area of a pattern. Minefinder, you do understand shade is surprisingly much the worst property you need to use to tell apart igneous rocks, hint components can substitute shade with only components in line with million in concentration of the component. If that weren't the case smokey quartz could be seen mafic somewhat than felsic, by means of its black shade.

Answer 3

Mineral composition. "A" is wrong because igneous rocks aren't cemented. "D" is wrong because only sedimentary rocks have fossils. "C" is PROBABLY wrong because igneous rocks aren't made up of multiple minerals. That last part is sort of a guess...

Answer 4

Go to Wikipedia, the free encyclopedia to understand more about igneous rocks.

Answer 5

mineral composition, plus other factors to identify the environment in which the rock cooled.

Answer 6

B and maybe C

If you want to spot an igneous rock use a scratch test, it will be harder then the average rock...