What kind of rock can you see through?
A very large number if the rock forming minerals allow the
transmission of light if sliced thinly enough. Some others are
translucent at larger scale for example quartz and calcite. However
in most rocks the size of the clasts or crystals is too small or
the presence of gas inclusions or other elements causes them to
become coloured, cloudy or otherwise opaque.
It is possible that it may be possible to see through a
pegmatite (pegmatites are a rare type of very coarsely crystalline
intrusive igneous rock) if the crystals are large enough.
As such in the vast majority of cases naturally occurring rocks
are opaque and can not be seen through.