Question

Why are all rocks not ores?

Answer 1

Ore- A mineral occurring in sufficient quantity and containing enough metal to permit its recovery and extraction at a profit.
Rocks- A rock is made up of 2 or more minerals. You need minerals to make rocks, but you don't need rocks to make minerals. All rocks are made of minerals. 

Answer 2

All rocks are not ore because rocks mixture of common minerals. Rocks can be hard or soft, as small as a grain or as large as a building a strong rock is only used to build house etc. we cannot get any minerals from them and they can be found at any place but in case of an ore it is a type of rock that contains sufficient minerals with important elements including metals that can be economically extracted from the rock. The ores are extracted from the earth through mining; they are then refined (often via smelting) to extract the valuable element, or elements.