Black sand and sandstone variants are now in the Biomes’o’Plenty add-on pack. I also refined existing white sandstone blocks as well as Vanillaccurate’s vanilla sandstone+red sandstone blocks with regards to their AO.
Here are a few captures using Kappa 4.1 E1 and Continuum 2.1 alpha build 12.
Notice how ambient occlusion gives depth to the white sandstone blocks that are in the shade (Continuum 3rd picture, Kappa 3rd picture), whereas black sandstone blocks facing the sun don’t exhibit such occlusion (Continuum 2nd picture, Kappa 2nd picture).
HardTop Vanillaccurate 