Natural Science in Archaeology

10.3 Salt (Halite) 225
does not yield just halite but also other salts. The order of evaporation in natural
saltpans is calcium carbonate (calcite), calcium sulfate (gypsum), sodium chloride
(halite), and potassium magnesium chloride (carnallite). Halite is usually the most
abundant. The composition of saltwater brine varies widely. Some would not be
suitable for salt production. Pliny realized and described the different raw materials
for salt production: rock salt beds from evaporite deposits, some brine waters, and
seawater. Large-scale boiling of brine to recover salt dates back to the Iron Age in
Europe. Also in the Iron Age salt was mined just south of Salzburg, Austria from
750 to 150 BCE. (Megaw et al. 2000).
Over most of the earth salt took little energy to exploit and was easily transported.
It can be recovered from seawater by boiling or evaporating the water. Salt
from Palmyra, in ancient Syria, was traded throughout the Persian Gulf. After the
collapse of the Roman Empire, metal mining almost ceased, but salt mining continued
because salt was vital in the human diet. The caravan route through the Libyan
Desert in the time of Herodotus was located so that it passed through salt oases. Salt
routes throughout the Near East, Europe, and Asia reflect the vital significance of
this mineral to the social and economic needs of human populations. The salt mines
of ancient India were the center of widespread trade. The salt of the port of Ostia,
near Rome, supplied some of the Roman needs. Those of Caesar’s soldiers who
were “worth their salt” received part of the pay (their salarium) in the form of salt.
The Romans also used salt medicinally in gum preparations for eye salves and for
mouth and gum sores.
Salt in Egypt was most likely obtained from saline lakes near the Nile Delta.
Pliny notes a lake near Memphis and sources at Pelusium (N.H. 31, 39; 74, 78). He
also notes a particular type of salt found in the desert between Egypt and Arabia
(Lucas 1989). Salt is also found as (1) an impurity in natron deposits of the Wadi
Natrun, and (2) with gypsum at the Oasis of Ammon. During the Ptolemaic Period
salt became a royal monopoly. The major locality for its manufacture gradually
shifted from Pelusium to the area around Lake Mareotis, near the ancient metropolis
of Alexandria. In addition to dietary uses, salt was employed as a drying agent and
preservative (for example, in preserving fish). Salt was employed in metallurgy for
refining gold and in the production of glazes. It also was used medicinally in the
New Kingdom, as attested in the Ebers Medical Papyrus. Although natron was the
principal mineral used in mummification, after the first century salt was interspersed
among mummy wrappings to aid desiccation. It was used in tanning processes both
in the Near East and in the classical world. Salt was marketed in lumps and bricks,
and blocks of salt are included in religious donation lists.
Salt was also important in Mesopotamia where it was used in religious offerings,
in medicines as an emetic, and in glass making and glazing. It was also used
to catalyze the burning of fuels (such as cattle dung) in baking ovens (Singer et al.
1954). It was added to oil in lamps in both Mesopotamia and Egypt to brighten the
flame and give it color (Herodotus 2, 180).
In prehistoric Europe the rock salt mines of the eastern Alps were a major source
of this commodity. German place names with “hall” or “halle” and Anglo-Saxon
“wich” frequently indicate a locality where salt production took place. The mines at