Amphiboles

name colour lustre Mohs hardness specific gravity

actinolite colourless to gray; darkens with increased Fe through green to black silky; oily 2.9–3.2 2.9–3.2

anthophyllite white, gray, green, or various shades of brown vitreous 5½–6 2.9–3.2

arfvedsonite dark bluish green to greenish black or black vitreous 34460 3–3.5

basaltic hornblende brown to black glassy 34460 3.2–3.3

common hornblende pale to dark green glassy 34460 3–3.4

cummingtonite dark green; brown silky 34460 3.1–3.6

glaucophane gray or lavender-blue vitreous 6 3.1–3.3

richterite brown, yellow, brownish red, pale to dark green vitreous 34460 3–3.4

riebeckite dark blue or black vitreous 5 3–3.4

name habit or form fracture or cleavage refractive indices crystal system

actinolite fibrous massive one perfect cleavage of 56 degrees alpha = 1.600–1.672

beta = 1.614–1.686

gamma = 1.627–1.693 monoclinic

anthophyllite fibrous or lamellar masses; bladed and prismatic crystal aggregates one perfect cleavage of 54 degrees alpha = 1.587–1.642

beta = 1.602–1.655

gamma = 1.613–1.661 orthorhombic

arfvedsonite long prisms; prismatic aggregates one perfect cleavage of 56 degrees alpha = 1.612–1.700

beta = 1.625–1.709

gamma = 1.630–1.710 monoclinic

basaltic hornblende massive one perfect cleavage of 56 degrees alpha = 1.622–1.690

beta = 1.672–1.730

gamma = 1.680–1.760 monoclinic

common hornblende massive one good cleavage of 56 degrees alpha = 1.615–1.705

beta = 1.618–1.714

gamma = 1.632–1.730 monoclinic

cummingtonite fibrous or lamellar massive one good cleavage of 55 degrees alpha = 1.643–1.688

beta = 1.658–1.711

gamma = 1.663–1.731 monoclinic

glaucophane fibrous or columnar massive one good cleavage of 58 degrees alpha = 1.606–1.661

beta = 1.622–1.667

gamma = 1.627–1.670 monoclinic

richterite elongated crystals one perfect cleavage of 56 degrees alpha = 1.605–1.685

beta = 1.618–1.700

gamma = 1.627–1.712 monoclinic

riebeckite longitudinally striated prismatic crystals; fibrous massive one good cleavage of 56 degrees alpha = 1.645–1.701

beta = 1.662–1.711

gamma = 1.668–1.717 monoclinic