What color would you mix with white to get sandstone?

The problem answering this question is that "sandstone" can be several different colors ranging from shades of pink to green to brown. Ithink of sandstone as a taupe, which is a mixture of brown and grey. When you add pure white to a color to make it lighter, it can take on a pastel look. I suggest you use a light cream instead of white and add very small amounts of brown and grey to arrive at the shade you want. And I mean VERY SMALL. You can always add more. Because cream has a little yellow and brown in it, start by adding the grey. Make sure it is NOT a blueish grey. Then add the brown little at a time til you arrive at a pale taupe.