(These are drawings from my first "Optics and Spectroscopy of Minerals" lab)
A grain of Quartz in Cross Polarized Light (XPL) showing Undulating Extinction (See how the colours are different with rotation? Yeah, that's what that's showing.)
This one is showing something called a "Becke Line" which is a line of light that appears between two minerals in Plain Polarized Light (PPL).
It is really bloody hard to draw a line of light with pencil crayons.
An opaque mineral grain. ...Meaning I got marks for drawing a little black blob.
Garnet, in XPL and PPL, to demonstrate that it is isotropic.
I was running out of time by this point - can you tell? XP Also, the XPL one demonstrates why I wish we were allowed to use markers for solid black portions, rather than pencil crayons.
Okay, not the most exciting sketch post ever, but.... whatever.