Color Green, blue-green

Mohs scale hardness 6-6.5

Color Purple, violet, dark purple

Mohs scale hardness 7–lower in impure varieties

Color: Pale-blue to Light Green, even white translucent

Mohs scale hardness 7.5 to 8

Color: Black / Grey

Kyanite specimens have a variable hardness. The long crystals have a Mohs hardness of about 4.5 to 5 if tested parallel to the length of a crystal, and a hardness of 6.5 to 7 if tested across the short dimension of a crystal.

Color: Blue and white streaks

Kyanite specimens have a variable hardness. The long crystals have a Mohs hardness of about 4.5 to 5 if tested parallel to the length of a crystal, and a hardness of 6.5 to 7 if tested across the short dimension of a crystal.

Mohs hardness of 3, a specific gravity of 2.71 and, in crystalline varieties, a vitreous luster. Color is white or none, though shades of gray, red, orange, yellow, green, blue, violet, brown, or even black can occur when the mineral is charged with impurities