dragon stone. septaria mineral stone texture with fissures filled with calcite crystals

radiant septaria dragon stone calcite crystals aggregate amulet atomic structure pyrite concentration minerals concretion connate crystal crystalline crystallization diffraction dispersion dolomite earth fissures fossils fractures gemstone geode geology grown together hardness inorganic irregular shapes stripes limestone rock marly mineral mineralogy polished polygonal precious radial science semiprecious septarian nodules septars specimen turtle unpolished volcano