[pcottraux]

It gives off warmth too and lasts a long time.

You think that's something, look at me: The darker color and density increase with an increase in the iron content. Biotite tends to form in a wider range of conditions than phlogopite which is limited mostly to ultramafic rocks and magnesium rich marbles and pegmatites.

[Hoodlum91]

OK, you're a little TOO into the rock game.