There is a possibility that the cinnabar ÿHgSÿ pigment used in the Takamatsuzuka tumulus was dug from the old Yamato mine. To search for a key
to the solution, the microstructures of a cinnabar ore produced in the old Yamato mercury mine has been investigated. The specimen was taken from an
old stockpile at the mine. An X-ray diffractometer, a scanning electron microscope, a transmission electron microscope, and an energy dispersive X-ray
spectrometer were used to clarify the microstructures. The ore contains HgS as the main mineral, and ÿSiO2, cristobalite ÿSiO2ÿ, augite, kaolinite, albite
and other minerals were detected. HgS crystals are buried in the vacant space ÿssureÿ of the ore, and the crystals are distributed similarly to a chain of
islands. The size of an ÿSiO2 hexagonal column found in the ore is 5-10 μm. HgS con-tains Si, Al, and Fe as impurity.ÿÿdoi