The main activities include exploration for metals such as gold, silver, and copper.

It is backed up by precious metals such as gold or silver.

They also were in search of trading goods such as gold, silver and spices.

This is one reason why metallic inks, such as gold or silver, were common.

Although the river looks very clean, it has high levels of some metals such as lead, zinc and silver.

They are also famous for measuring monetary objects such as gold and silver.

These are used for trading precious metals such as gold and silver.

The growth usually happens because an important resource such as gold, silver, or oil is found close to the town.

Other heavy metals such as gold and silver are also used.

Some metals such as gold and silver give the strings a different sound.