What is commonly understood as sand, has not much to do with little glass balls, even though here we have glass balls. A very special type of sand you can say,

What is commonly understood as sand, has not much to do with little glass balls, even though here we have glass balls. A very special type of sand you can say, but not common "sand". But I feel no need to go more into pedantery here ... if this is sand to you, then I am fine with it.