This is a 10 cm long sample of hornblende. One of the key properties for identifying hornblende is the angle between the two main cleabages. That angle is about 60 and 120 deg -- best scene near annotation notes #1 and #2. (In contrast, dark colored pyroxene, which otherwise might be confused with hornblende has cleavage angles near 90 deg.) Masked bg, highest setting alignmnet, dense cloud high, standard for others.