What is the basic cause of ocean tides?

Ocean tides are a result of three things, the sun, the moon, and the rotation of Earth. Tides don't just apply to the ocean and applies to all things that rotate the way they do and have a gravitational field that varies. This includes solid objects on Earth too, but it's not easily seen because it's not like water.

Answer feldspar,quartz,mica and amphibole;

Build a market-oriented economy;