DetailsOne of the most common rocks, and an important one for students. Basalt is a fine grain rock with a crystalline structure. Typically black in colour due to the abundance of iron within the rock, basalt forms when magma cools quickly near the surface of the planet hence the small crystal texture. These particular samples come from Scotland and are dated at the Tertiary period. Specimens are supplied in polythene bags in lots of 1 kg and are come with an information label.