Cobalt may
seem innocent, peacefully hidden near the center of the periodic table, but in
reality this element, commonly known for the beautiful blue pigment it
produces, is deadly.
The name
cobalt is sinister in itself. It comes from the German word for the element,
Kobold, which means “goblin” or “evil spirit.” German miners gave cobalt this
name since mining cobalt was very dangerous. Mining any element is hazardous to
some degree but cobalt is particularly nasty since a toxic gas (arsenic
trioxide) often occurs with cobalt in nature
.
Cobalt is
still mined today, mainly for use in smartphones. No doubt modern miners there
would agree that Kobold is a suitable name. Cobalt miners, often children, work
in perilous conditions, risking permanent lung damage earning about a dollar a
day. Cobalt is in high demand due to its value as a component of super alloys,
metal alloys that resist rusting and retain their properties at high
temperatures. Super alloys have a variety of uses including forming parts of electronics
and jet engines.
Cobalt
isn’t only dangerous to miners. Cobalt-60, a radioactive isotope of cobalt,
could potentially wipe out the entire human race. Leo Szilard, a scientist who
worked on the Manhattan Project, figured out that an explosion of a cobalt-60
dirty bomb would kill all life in the vicinity of the explosion once it
exploded, and would continue killing all life that ventured in the area for about 90
years. A cobalt-60 dirty bomb kills with heat like a normal nuclear bomb, but
it has a hidden weapon that keeps it deadly for decades: gamma radiation.
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| A plastic isotope container containing cobalt-60 image used under creative commons |
Most radioactive
elements emit gamma rays for a few days, but cobalt is special. It keeps
emitting deadly gamma rays for decades. These gamma rays mix up the chromosomes
in our white blood cells either killing them or giving them cancer, making us
vulnerable to disease. Szilard estimated that if one tenth of an ounce of
cobalt-60 was sprinkled over every square mile of earth, all of humankind would
perish. Thankfully no one has attempted to make cobalt-60 nuclear weapons yet,
as far as we know.
Cobalt-60,
despite its dangers, can also be used to help humans. Its radioactive properties are used to treat cancer, preserve
food through food irradiation, and produce powerful X-rays to see through
metals.
These are
modern uses of cobalt, but humans have been using non-radioactive isotopes of
cobalt since ancient times. Back then, cobalt was mainly used for dye. The
ancient Chinese used cobalt blue in their pottery glazes. The ancient Egyptians
probably used cobalt too since a small glass object colored with cobalt was
found in Pharaoh Tutankhamen’s tomb. In addition to producing pretty blue dye,
cobalt is one of the three naturally occurring magnetic elements
.
The
alchemists used cobalt in their experiments, but they attributed its properties
and beautiful blue color to copper or bismuth. It wasn’t until 1730 that Georg
Brandt discovered cobalt to be a unique element making cobalt the first element
discovered that the alchemists hadn’t already isolated and named.
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| Cobalt Blue a public domain image |
The
earliest use of cobalt, long before Georg Brandt or even the ancient Chinese, is
the element’s use in the human body. Cobalt is vital to human health as a trace
metal. We need it to form enzymes and produce vitamin B-12. It’s kind of crazy
that one isotope of cobalt could kill us all, but we need another to survive.
