"Treasure is -
(a) any object at least 300 years old when found which -
(i) is not a coin but has metallic content of which at least 10 per cent by weight is precious metal;
(ii) when found, is one of at least two coins in the same find which are at least 300 years old at the time and have that percentage of precious metal; or
(iii) when found, is one of at least ten coins in the same find which are at least 300 years old at that time;"
"Any object at least 200 years old when found which belongs to a designated class."
Treasure does not include objects which are -
(a) unworked natural objects or
(b) minerals as extracted from a natural deposit."