Massive colorless aggregate of fine acicular Quartz. Chalcedony is classified into 3 species based on optical properties: Chalcedonite (common), Quartzine (rare), and Mogánite (Moganite) (very rare). Each fiber of length-slow chalcedony is formed by stacked small quartz crystals parallel to the c-axis, and that of length-fast chalcedony is by stacked small quartz crystals perpendicular to the c-axis.
Year of discovery: 1546 (Kadiköy (Chalcedon), Turkey), 1894 (Japan)
Locality list: 346 localities of chalcedony