Rocks are one of the easiest subjects to draw, if you understand light and shadow. Making a rock look realistic isn't hard. They don't move. You can draw from real ones. A little pebble can become a boulder in your landscape, or even a mountain.
Pick a pebble or rock, and set it out with a light that's at an angle to it on your table. Move the light or the rock until it has an interesting shadow. Interesting shadows are distinct, easy to see, take up a reasonable area near the object and show a little of its shape.
If your pebble is rounded and smoothed from a river it may be a simple oval without any features or details. But if it's broken or odd shaped, turn it so those cracks, shadowed indentations and details show.
Sketch the rock with your pencil, lightly. Sketch the outline of the shadow and of any shadows on the rock, as well as cracks and details. Take your time and try to get the shape of the rock accurate in your contour drawing. This is like other still life drawing, the more often you draw one particular rock, the more accurately you'll draw any rocks. Odd shapes are sometimes easier to get in proportion than perfect ovals, but give it some care and keep sketching till you have an accurate contour drawing.
My pebble is grayish-light, so I'm going to shade carefully now with the pencil. Pay attention to how dark or light the area on the rock is. Use your kneaded eraser to lighten areas if they get too dark by squishing it till a point is about the shape of the area you want light, then pressing down hard and lifting. Don't rub with the eraser too often unless it's to remove an unwanted smudge.
Within larger shadows are often smaller ones that have specific shapes. Do all the light shadow evenly and then start adding the details within the lighter shadow area. The very darkest shadows are within cracks or where the edge of the shadow meets the rock under the rock. Take as much time as you need to get these shadow details as accurate as possible. Every rock is a little different and the more different rocks you draw in pencil, the easier it is to get this complex shading.
This is also good practice for doing human features or animals or anything else where proportions matter. Because you may set out to get it exactly right, but get some proportion wrong, it won't matter as much when you show your drawings to people. It'll still look like a rock as long as you place the darkest shadow at the edge where the rock meets the surface it's sitting on and all the shadows on the side away from the rock. We'll do imaginary rocks in another step.
You can copy my rock, but it may be more useful drawing your own pebbles from life because you'll be able to see where you got it accurate or not.
I used a very soft 9B pencil for this example, so it would scan better. H pencils are lighter and harder the higher the number, H is softer than 3H and 9H is very faint and light but holds a hard point. H pencils are good for underlines under inking. HB is the normal No. 2 pencil you're used to getting free from banks and stores. B range pencils are blacker -- softer, smudgier and darker. Using a wide variety of pencils in a pencil drawing can give you more detail and a range of different effects.
Sketch the outline of your rock again with its shadows, repeat Step One, but draw very lightly or use an H range pencil and draw very lightly. My second sketch is too faint to scan, but it looks like Step One with very light lines. Draw from looking at the rock again rather than copying your previous drawing. This will help you get its proportions and details accurate. You may notice details the second time that you missed before, or correct a misplaced shadow.
This doesn't mean your first drawing wasn't good! It means that the more often you draw a particular object from life, the more you will get to know it's quirks and details. Don't shade this contour drawing, we'll do that with a pen.
Go heavy right where the shadow of the rock meets the rock, to imply that deep dark edge of shadow. Then do the rest of the outline, pressing lighter and heavier in places to be expressive -- go lightest where the rock is lightest. Add heavy marks for the cracks.
Use hatching and crosshatching to fill in the shadow areas, but don't outline the shadow areas with the pen. Let the edges of the hatching trail off like my example to show it's more of a blurry edge than the edge of the rock itself. Simplify the shadows if your pen width is thick and the rock drawing is small, don't try to get the subtleties that worked with a pencil. This will help keep the areas of shadow looking the right value instead of darkening too much by lines too close together or overlapping too often.
Rocks from imagination are something that will get easier the more often you draw rocks from real pebbles and rocks. It is easy for them to get stylized, oversimplified or look like other things. But let's do some simple rounded river rocks from imagination to show how it's possible to include them in anything, even doodles. My cat just stole my pebble anyway to play with it on the floor.
Sketch a loose oval. It does not need to be perfect. Sketch a larger one behind it. Then make up a couple of overlapping irregular shapes, maybe rounded, maybe jagged as if they broke. Here is an example of some rock outlines from imagination, just the outlines.
Shade the rocks with simple hatching at an angle, no crosshatching, as the line width in relation to this drawing is very heavy. You can do this very small with a very fine point pen too, and it will look great in the background of a detailed pen and ink drawing. Rocks are not often the main subject in art, more often they're background details for an animal climbing over them or for plants or people.
This time I did the shadows of the rocks on the ground very stark and black, the way I first learned to do them from an astronomical painter. Very dark shadows make the light look bright and directional.
We'll add some more pen colors in the next step, to show different types of rocks and how shadows look on rocks in different colors.
Rocks in color are fun, you can show stripes and different variations within the rocks themselves. Let's do some striped sedimentary rocks. You don't need to use the same colors I did, use whatever shades of brown, gold, gray, red-brown and red you have. One little pebble is bright red like jasper because you do find bright red rocks sometimes in nature.
Sketch various rock outlines, some rounded and some not, using different colors for them. These are the colors that will become the predominant colors of those rocks, we want some variety. Copy my sketch or just make up your own arrangement -- or take a handful of pebbles, arrange them and come closest to their real colors. Don't sketch in the contours of the shadows yet, we'll do that in the next step.
With the base color of the rock, draw in some stripes. To make some of the rocks striped, follow the contours of the three dimensional shape of the rock. Make the stripes follow its shape. Draw them at an angle, curve them at the edges and use them to show that the rock is three dimensional. Do the stripes before any shadows on striped rocks.
Think of topological maps. The shape of a worn striped rock like an agate looks like that -- the projections are smaller circles and shapes and ovals surrounded by a larger layer that may connect more than one.
Make the stripes different widths and leave plenty of room between some of them. Add more stripes following the same pattern in related colors, the way you see them on agates and other striped polished stones. Here's how they look with the stripes on. Some of them are solid colored and have simple shading in light and dark versions of the same color. Just draw a smaller oval and place it slightly to one side, leave it open for highlight color, and go over the shadowing color with the highlight color to give it smoothness.
We have not added Cast Shadows to these rocks yet, that's the next step. Cast shadows are the shadow on the ground, the shadow made by the object on whatever it's sitting on or next to. The gray rock has some shapes implied by shadows in the white stripes.
Using a dark muted blue, draw the cast shadows as solidly as in the black shadows example in Step Five. Fill in the ground with whatever color you want the sand or dirt, preferably a light color so that the rocks stand out. Fill the sky with gray or light blue. Shade the rocks with light blue or blue-violet, or with gray. Shade solidly where you would have used crosshatching but use a light color so that it doesn't turn black.
While this may look greenish on some yellow areas, that can happen. Test your colors first and if you don't like a combination, test other combinations till you get it the way you want. You may want to leave the shadow areas of yellow rocks uncolored until you shadow them, creating a dramatic contrast between yellow areas and blued shadow areas. Or just accept the greenish cast as I did.
Do many rock sketches in color or black and white mediums. Range from quick cartoon renderings where the main element is a single shade of shadow and highlight to give it three dimensional depth to detailed pencil drawings of specific rocks that look so real you could pick them up off the page. The more often you draw rocks from life, the easier it is to draw rocks from imagination.
If you want a marker rock to look shiny, sketch in white highlights with white watercolor or acrylic after they're finished, sharp white highlights over the whole thing as it is. Pay attention to where those highlights really are on your polished rock samples. Keep the light direction above and to one side for the best rendering to show rocks are three dimensional. Make the cast shadows distinct and strong to imply three dimensions. It can work just to do a small oval and its cast shadow for a pebble on the ground as a background element. For a pop art effect, use complementary bright colors for a dramatic rendering. Use bright yellow rocks and deep purple shadows or bright orange rocks and deep blue shadows, you can do entire drawings in just strong complementary colors to give a gorgeous pop art look.
Move your cat off the drawing table when working, or risk having your pens and still life objects batted around all over the place. Do not use spray workable matte fixative in areas with open flame or lit cigarettes. Make sure you have adequate ventilation, preferably spray outside or near an open window.