I don't want to always say the same, but is it carbon again?
I am a building block, used to construct larger things, yet of these very building blocks am I built.
-Carbon is a fundamental atom of many structures, also it makes macroscopic carbon.
I have many shapes and sizes. I can be thick or thin. I can be many colours.
-All of these may be reference to graphite/diamond and colored diamonds.
I have no wings, yet I fly to far fields.
-When in gaseous molecules, it can fly very far.
I have no arms, yet I bear heavy burdens.
-Natural diamonds form at very high pressures and temperatures.
I have no tongue, yet I tell of terrible ancient tales.
-14C is used to date organic samples.
I am sometimes deposited in various locations, but in these locations I reside for only a short time.
-Deposited carbon is transformed in CO2 by some organisms.
In one of my forms, you will see me and recognise me. In another of my forms, you will see me without recognition. I am unknown in another of my forms.
-We can detect 14C with radiotechniques, and we know 12C is everywhere even when we cannot individually recognise it. 21C is an isotope with a mean life shorter than 30 ns, so I assume that it's never been seen, so unknown, even when its existence is proven.
I can be very comforting, but also very unpleasant.
-CO2 has been used as anaestethic, but CO smells like rotten eggs.
My appearance is often awaited, even when I am present in abundance.
-People search for carbon beyond the earth, but it's difficult for us to get there and find it, even when in abundance.