Green to light yellow green 3-5mm plates of Clintonite, a brittle mica. Brittle micas do have flexible plates, so this is a hint to its identification.
Clintonite is a phyllosilicate, a mica group member subclassified as a brittle, trioctahedral Mica. Ca, Na, K occupies the interlayer positions while Mg, Fe2+, Al, Fe3+, Mn in the octahedral positions.
Clintonite occurs as tabular, pseudohexagonal, foliated, lamellar radiate crystals. Occurs cheifly in association with calcite, idocrase, grossular, spinel, phlogopite in crystalline limestones i.e. Crestmore (Encycl. of Min.)