Beautiful Scolecite Geode from India. Scolecite is a mineral, a hydrated calcium and aluminum silicate (tectosilicate), belonging to the zeolite group. Scolecite is the typical fibrous zeolite; it has a monoclinic crystal structure, characterized by a single twofold axis and a plane of symmetry. Scolecite has a density of 2.3 g/cm³ and a hardness of 5.5 on the Mohs scale. It displays good cleavage and a conchoidal fracture. It occurs as slender striated prismatic crystals, white or colorless, commonly arranged in fan-shaped aggregates or fibrous-radiating masses. Scolecite crystals are generally thicker and more rod-like than those of natrolite, although the two minerals can be difficult to distinguish with the naked eye due to their very similar appearance.