A mineral deposit is the showing of any type of mineral whether it has value or is just of scientific interest. An ore deposit is a mineral deposit that has an economic value as well as a scientific value.
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| The copper mineral malachite Photo by Rob Lavinsky | 
There are times when you can actually have a very large mineral deposit worth millions of dollars, but because of its location or the cost of production to mineral deposit is not classified as ore. A good example of this is a group of prospectors found a copper deposit in northern Canada 
This example drives home the difference between ore deposits and mineral deposits to the extent that the prospectors of all eventually called this the $100,000,000. nuisance.