All sand dunes desirable for sandboarding have several things in common. They all have an abundant source of dry sand, a method to transport and deposit the sand, and an area in which to deposit the sand. These dunes took hundreds of years to form and all formed around bodies of water. Over many years, wind and water action weathered the sand, forming small, uniform, rounded grains, perfect for sandboarding.
Dunes around mines and volcanic sites are not ideal for sandboarding. These dunes were formed very quickly by fracturing the rock into small fragments, either by nature or man. Each of those grains of sand has small, sharp edges similar to pieces of broken glass. This type of sand will dig into your sandboard causing uneccessary friction when sandboarding, slowing you down. It can also damage the bottom of your board. Ideal dunes for sandboarding are natural wind and water formed sand dunes. These will give you faster runs and a longer board life.
There are two main sides to a dunes. There is the windward slope, called the stoss. This side is longer and less steep. As sand is pushed up the stoss slope it falls over the crest and onto the leeward slope, called the slip face. The slip face is shorter and steeper, making it ideal for sandboarding.