Phyllosilicate - Monoclinic - Mica group member. Ordinary (True or Common) Mica - Dioctahderal with Al3+,, OH at the (A) and dominant NH4>K at the interlayer position.
In Bernard & Hrysl "Minerals and Their Localities" describe this mineral as white to yellow to green clayed aggregates composed of tiny flakes. Mindat list five worlwide localties, one in the USA as Five MIle Pass, Utah. Maybe our friend Joe Marty will collect some fo this stuff for us.