A french mineralogist, René Just Haüy in 1801 named amphibole from the greek amphibolos (ambiguous) word. It is an interesting name, because amphibole is not just a name of one mineral, it is a mineral group. For a long time mineralogists considered the black, columnar growth minerals as schorl (black tourmaline). These non-ore minerals were useless for german miners who named them Hornblende. Like the similar looking pyroxenes, amphiboles are rock-forming minerals. They can be distinguished with the angles (90/120 degrees) between their cleavage planes. The amphibole group involves several minerals. They crystallize mostly in monoclinic (amphibole, tremolite, actinolite etc.) or rhombic (anthophyllite etc.) crystal symmetry. They can be found in volcanic and metamorphic rocks in massive or individual crystals bordered by sides. Localities: Czech Republic, Germany, Norway, USA, Madagascar, etc.