Arsenic is a silvery grey semi-metal. In nature it occurs as a
brittle metallic mineral, but in the laboratory it can be made
into a white powder - and this is the kind of arsenic that
poisoners have used since the days of the Ancient Greeks.
Arsenic rarely Occurs as a native element and is more
typically found in sulphides and sulphosalts such as
arsenopyrite, orpirnenr, realgar and tennantite. When it is
found, native arsenic is usually mixed in with
silver and antimony. Arsenic is a
common by-product when silver ore is
mined. It usually Occursin masses with
onion-like layers called 'shelly' arsenic
or 'scherbencobalt', or in kidney-like
crusts. Very occasionally arsenic crystals
are found, typically trigonal in form.
However, arsenic exhibits polymorphism
(has more than one shape) and in Saxony,
Germany, some orrhorhombic crystals have
been found. These orthorhombic arsenic
crystals are called arsenolamprite.