Chrome Oxide Green is a paint I hear little about and do not understand why. I find it fundamental to my landscape paintings. It is a mid value, mid chroma, very opaque inorganic pigment and is the only single pigment Green paint available that is located in the foliage quadrant of a colour wheel. In fact it is just about dead center in the foliage area. Sap Green and Hookers Green are more popular and close in Value, Hue and Chroma but are a mixture of pigments.
For my Landscape Greens I start with Chrome Oxide Green and tweak it warmer or colder, lighter or darker, more or less saturated etc. I use Cadmium Yellow Light or Hansa Yellow Light and Thalo Green to lighten and or saturate the Chrome Oxide Green. I use these two yellow paints because one, Cadmium Yellow light, is reasonably Opaque and the other, Hansa Yellow light, is Transparent, giving me two different effects. These three paints give me a simple miniature gamut of mid to saturated foliage Greens. I can use mix any Blue into the mixture to pull the Green to a Blue-Green and I use Red Oxide to further de-saturate it. I believe this method is much simpler than mixing Yellow and Blue then adjusting the Chroma with Red.
Chrome Oxide Green also has a second fundamental use for me. It will de-saturate virtually any Red from Cadmium Red Light right through to Dioxazine Purple. You can spend hours, days, years trying to memorize what is the correct mixing complement for all the available Reds or you can simply use Chrome Oxide Green.
Another fundamental paint to my palette is Red Oxide that is similar to Chrome Oxide Green in that it will de-saturate virtually any Green through to Blue-Green. You can see my Standard Earth Palette here.