The best size of gravel depends on the intended landscaping use and type of rock. To line or mulch a garden bed with smooth gravel, use rocks 1- to 2-inches in diameter. Generally, 10 to 18 mm (about ...

Igneous rocks close igneous rockIgneous rocks ... causing them to change into another type of rock. They are usually resistant to weathering and erosion and are therefore very hard-wearing.

There are over 5,000 known types of minerals ... combinations of these minerals are endless. Rocks also differ based on how they were formed. Igneous rocks form out of cooling lava or magma.

An igneous rock has come ... the geographical distribution of the rocks, their connection with crust-movements, and the sequence of eruption of different types at a given centre.