How can a non-geologist identify a rock?

Question

I found a rock on a beach in north-east Evia, Greece. Half is light gray, and half is dark gray. There are white (or very light gray) thin lines that form swirls throughout, crossing the light/dark gray boundary in the main body of the rock. To me, they look like fossilized leaves or something similar.What is the best way to work out what this is? There seems to be an abundance of different rock types, many colors, but there are many similar stones to this one, all worn into smooth rounded pebbles.

Answer 1

Hi! The best way to do this is to look up a 'rock identification chart'-- the rock is clearly rounded by the ocean if you found it on a beach. :) This makes things a little harder, but still possible!

It sounds like the white line you see could be a result of metamorphism. Is there a pattern to the white line (foliation)? Do you see crystals that 'interlock' (igneous or metamorphic) or little rounded pieces of rock in a random orientation (sedimentary)?

Based on the way you described it I would say it is an igneous rock, but looking up a rock identification chart and using it while looking at your rock would be the best way to identify it!