Mixing Cadmium orange and Thalo blue together creates olive green. Adding more Cadmium orange gives the pigment a more olive green color, while adding more Thalo blue yields a bluish-green color. Another option is to blend yellow or ochre with ivory black or Payne's grey.
In general, mixing blue and yellow together yields shades of green. There are other combinations of colors that can be blended to produce green. It was discovered by accident that adding yellow to black gives a dark, earthy green color. Blending different shades of black and yellow yields various shades of green. Experimenting with shades of green is a technique done by artists when painting landscapes.