A naturally occurring white, lustrous metal, widely distributed
in nature, but the total amount is quite small when compared
with other metals, constituting only some 0.05 parts per million
of the Earth's crust. Practically all sulphides of lead, copper,
and zinc contain some silver.
Obtained from crushed silver bearing ore. The actual method
of recovery from the ore depends on which metal is predominant
in the ore but normally ends by electrolysis using one of two
techniques, either the Moebius or Thum Balbach systems. The
chief difference being that the electrodes are positioned vertically
in the Moebius system and horizontally in the Thum Balbach.
As a food additive it is used solely for external decoration
where it can be found on chocolate confectionery, in the covering
of dragées and the decoration of sugar-coated flour confectionery.
Long, regular consumption can lead to kidney damage and a blue-grey
discoloration of the eyes, nose and nasal septum, throat and
skin.
Not permitted in Australia.