The Horn of the Unicorn has MAGICAL POWERS!

The horn of the unicorn has been sought after for centuries. In the
west, it was thought to have magical properties, and could purify poisons.

Therefore, it was a very valuable commodity to have.  Pope Paul III is said
to have paid 12,000 pieces of gold for one, but James I of England got a
much better deal for his, only paying 10,000 pounds Sterling for one.  The
horn of the narwhal was a common substitute for that of the unicorn for
those unscrupulous businessmen.

 Because of that problem, a common test to determine the validity of a
unicorn horn was to use its magical properties of purification.  David De
Pomis wrote, 'There is very little of the true horn to be found, most of
that which is sold as such being either stag's horn, or elephant's tusk.  A
true test by which one may know the genuine horn from the false:  Place the
horn in a vessel of any sort of material you like, and with it three or
four large and live scorpions, keeping the vessel covered.  If you find
four hours later that the scorpions are dead or almost lifeless, the horn
is a good one, and there is not enough money in the world to pay for it'.