why do metamorphic rocks rarely contain fossils??

Answer 1

Simple answer: Fossils are delicate.

Only 1% of what des becomes a fossil.

99% of all fossils are found in sedimentary rocks.

The processes of igenous and metamorphic rock a) are too burtual for preservation and b)do not happen in places where preservation does (i.e. too deep).

Answer 2

Metamorphic rocks are compsed of a rock that has been reheated and cooled quickly, thus starting the "time clock" over for that rock.

The reheating process does not completely melt the rock into a lava form but it is hot enough to allow compression from the earth and new minerals to enter, thus, creating a different rock compound all together.

An example would be to put a taffy (made from molasses) in a microwave along with gum, melt them and mix them together and then freeze them. If either piece of candy had any markings on them they would now be gone and you have a new candy compound without any type of identifying mark. (never tried this,don't know how well it would work, but that's what my Geology Professor said)