So, my husband, who is a geolgist, says that it is "real sand", but it is washed. They wash out all the fine materials, which makes the texture feel different - and why you can't build good sand castles. It actually works as a really good filter and makes the pool even cleaner. We are DVC members, so we are fortunate to be able to stay at the BC frequently. It is our favorite resort in WDW, bar none.
This was a great question...I learned a bunch today too!
Michelle