A 550 million year old source of minerals and trace elements for your horse or pony.  Mined from the Khewra Salt Mines at the foot of the Himalayan mountains in Pakistan, and transported by truck and train, these mines give the local people one of their main sources of income.  It is said that Alexander the Great discovered the mines when he travelled through South Asia, but in fact it was the horses that first alerted him to this rich mineral source!  When Alexander's army stopped to rest the horses started licking the stones, one of the soldiers noticed this and tasted the rock stone and realised it was salty, thus leading to the discovery of the mines.