Hveragerthi
I had not heard that name until yesterday when I was talking to someone about zeolites (aluminum silicates). This appears to very similar as it is listed as a sodium calcium alumino-silicate
http://www.azomiteinternational.com/WIA/MineralAnalysis/USA_Analysis.html
I know a lot of people are in to ingesting aluminum silicates, but I am not one of those people. I can think of plenty of nutrition sources and fertilizers that do not contain significant if any aluminum. I feel safer sticking to those.