Color is usually dark blue to black. Luster is vitreous or silky in fibrous forms. Crystals are translucent. Crystal Habits include slender prismatic to acicular, often aggregated crystals, columnar, granular and fibrous, asbestiform masses. A moss-like aggregate habit has been described when found in some igneous rocks.
Fracture is splintery to uneven.
Hardness is 5 - 6. Streak is blue-gray. Weakly pleochroic and crystals are striated lengthwise. Associated Minerals are nepheline , quartz , almandine , aegirine , feldspars , micas and hematite . Best Field Indicators are crystal habit, color, streak, cleavage and hardness.