Amphibole group - Group of minerals that contain iron, magnesium, silicon, oxygen, and hydroxyl (OH). They may also contain calcium, sodium, and lithium. The amphiboles have prismatic cleavage, and one can note the angle of 56° and 124°, which distinguishes it pyroxenes, which are at 87° and 93° (almost perpendicular). The amphiboles are very similar to the pyroxenes, and the minerals belonging to each group many times cannot be distinguished by ordinary methods. Generally, though, the amphiboles occur in longer, thinner crystals than the pyroxenes. The pyroxenes contain the same elements that the amphiboles do, except they lack hydroxyl, which alters both physical and chemical properties.

The amphibole group is in the inosilicate subdivision of the silicates group.