Actinolite

Actinolite is an amphibole silicate mineral with the chemical formula Ca₂Si₈O₂₂(OH)₂. Wikipedia

Cleavage: perfect along

Hardness: 5–6

2V angle: 78–82° (calc), 84–73° (meas)

Color: pale to dark green, yellowish green, blue and black. White or grey when in asbestos

Crystal class: Prismatic (2/m); (same H-M symbol)

Crystal habit: bladed, fibrous, radial

Crystal system: Monoclinic