Pentagonite

Pentagonite is a rare silicate mineral. It was named for the unusual twinning which produces an apparent five-fold symmetry. It is a dimorph of cavansite. It has also been reported from the Puna area of India. It occurs as fracture and cavity fillings in tuff and basalt. It occurs with cavansite, heulandite, stilbite, analcime, apophyllite and calcite. It comes in deep blue color. 
Color: Blue