Color: Red ochre is an earth pigment that contains hydrated iron oxide.  When you burn yellow ochre in an oven, it becomes red, creating a red ochre.  Much of the variance of color comes by how hot/long the burn is as well as where the yellow ochre is from.

Opacity:  Very opaque

Uses:  Red ochre is often mixed with glazes for a variety of decorative finishes.  It is commonly used to create tonalities in faux marble.  Because of its opacity, it does not work well with woodgraining (use raw sienna instead).   

**Red ochre is very strong and can overtake a color quite quickly.  Along with Prussian blue, red ochre is the most potent color.   That is why you’ll see snap lines made with red ochre chalk ― because it a strong color.