Is Bentonite Clay supposed to be "radioactive"

[NancyK55@aol.com]

Let me start by admitting that everything is supposed to have some degree of
radioactivity.  BUT I did not expect that an incoming shipment of bentonite
clay would be radioactive enough to set off the incoming shipment portal
monitors at my local foundry, as it did.

Have any of you encountered noticeable levels of radioactivity (>2xbkg)
associated with bentonite clay?  I did not find bentonite clays identified as
a mineral source of unusual radioactivity in the collection of NRCP handbooks
on my bookshelf.