Colorado has plenty stretches of soil that is layered in 2 to 8 different colors.
If you’re grinding your own pigments like Black Pigment or PREPARING BONE CHARCOAL, you’ll need a heavy-duty mortar and pestle set. You can collect plenty of decent pigments that need no treatment other than grinding. It’s much easier to find pure mineral pigments in small amounts and with most, a little goes a long way.
Depending on where you are in COLORADO, you may be looking at the Jurassic Morrison Formation, multicolored shale that is famous for its dinosaur bones, petrified wood, and uranium (there’s a signed road cut along the interstate near Golden). It is basically clay (mostly sticky bentonite from weathered volcanic ash) with various impurities: iron oxides (reds and yellows), manganese oxides (purples and grays), reduced iron (green). If it’s soft and not gritty (no quartz), just grind it up and use it. Although rare, patches of pale yellow powder (sulfur) and bright yellow
(radioactive carnotite or “yellowcake”) should be avoided. Many sedimentary rocks (especially in the Colorado Plateau canyon country) will contain thin dark red layers of pure hematite (red ocher). Old mine dumps are good places to look, too – you might find hematite, brown iron oxides, magnetite, and perhaps green copper ores. Bluffs on the High Plains of eastern COLORADO are good for small dark semi-metallic looking concretions – a challenge to grind, but very pure pigment. Black ones are manganese oxide, dark brown ones are iron manganese oxides (raw umber), lighter brown are goethite (brown iron oxide).
Black Pigment PREPARING BONE CHARCOAL:
Any kind of bones are fine for Black Pigment. Weathered desert bones work great but you can use cooked bones too. Crush the bones with a hammer into 1/2″ to 1″ pieces. Wrap the fragments in foil to make a small package (start with something no bigger than 6″ long – they’ll burn more evenly in small amounts), set the package on rocks or the sidewalk, and heat with a small propane blowtorch (such as Bernz-o-matic, available in hardware stores.) Torch flame should be horizontal – it will go out if you hold the torch with the flame pointed at the ground. The bones will smoke a bit and smell awful. Cool the package and check it periodically – the bones should be black with a bit of white ash and very little brown area left. The whole process takes ten or fifteen minutes. Charred bones are very brittle and easy to grind make beautiful black pigment. The charred bone pigment is a mixture of amorphous carbon (black, provides most of the color), various phosphates (brown – provides intensity, transparency, stickiness, and quick-dry properties of this pigment), and calcium carbonate (white powder, transparent when wet, gives this pigment its smoothness). If all else fails, chuck the package in the fireplace while you watch a movie, and retrieve it the next morning. Thank you Lorena B. Moore http://www.mineralarts.com
You could easily become a fanatic about this – collecting several vials, each labeled with the type of bone. They all look the same in a painting but could be chosen for symbolic value. I have a few ashes from my sister’s death and was thinking of using them in an Icon! Just Thinking…. Uuuhhmmmm.