Oh man it feels good to be able to write that! Sounds exactly like one of the old master drawings I've been poring over endlessly in Master Class in Figure Drawing (which I finished reading last night - need to draw from it some).
Did a skull study today from the skull replica I have just named Bucky (in reference to the teeth) (oh, and no, I didn't draw them that way - did a little artistic dental work on him). I love the way it looks - 3 important things I handled well thanks to my recent studies - blocked in the basic forms first, then shaded along the major plane breaks, and finally wrapped my chalk strokes around the form. Oh, also used the powerfully form-producing core shadow technique.
I love the way a chalk drawing looks on good toothy paper - it sparkles - little dots of white and black over the various shades of gray.
I thought about old skull studies I've done - all very weak because I wasn't well versed in the classical techniques I described above and didn't understand to keep shadow planes uniformly dark and light planes uniformly light aide from some detail shading that isn't far from the value of the plane itself.
Also thought about old drawings I tried in conte crayon or colored pencils on tinted paper - very weak as well, for similar reasons - though in this case it's also because I hadn't developed a strong sense of how to properly draw form. I just ordered a set of conte crayons and some pastel paper and can hardly wait - and I was right about one thing - the conte crayons are waxier than regular chalk sketch sticks and don't produce much dust.
Now I fully understand why you need to be able to draw like this before you can paint.
Some exercises I'd like to try soon - limited-palette, limited-value sketches on the tablet and with selected colors of various drawing media, like pastel or oil pastel.