Natural Science in Archaeology

228 10 Abrasives, Salt, Shells, and Miscellaneous Geologic Raw Materials
Fig. 10.3 Sources of salt in
Ming Dynasty China
the Ming Dynasty (Fig. 10.3). In the quest for salt, the Chinese originated deep drilling,
up to about 1500 m, by the first century BCE. During the Ching Period the salt
supply was widely dispersed. Although four-fifths of the salt came from the coast,
one-fifth came from salt lakes, brine wells, saline rock, gypsum mines, and salty
earth. The spread of salt production in China had reached its maximum areal extent
in the earlier Ming Period (1368–1644) (Chiang 1976).
In Japan, the environment for salt production is poor. Although surrounded by
salt water, the islands of Japan lack coastal flats for evaporation fields and reliable
sunshine without too much rain. As a result, at least for the last 1400 years,
the Japanese have relied on a two-step process for concentration and evaporation.
Seaweed soaked in seawater is dried and the salt that precipitates is rinsed off into
more seawater, producing a more concentrated brine that is evaporated by heating
in clay pots.
10.4 Natron
Natron is a naturally occurring mixture of sodium carbonate (NaCO 3 ) and
sodium bicarbonate (NaHCO 3 ). Strictly speaking, natron is NaCO 3 10H 2 O. The
first use of the term “natron” appears to be in the glazing of quartz and steatite
(Shortland et al. 2006b). The word (in Egyptian hieroglyphics “ntry”) is most likely
derived from the root “ntr”, indicating its association with religious and funerary