Color is usually white or colorless, but can be pale gray, blue, yellow or violet. Luster is vitreous to silky. Crystals are transparent to translucent. Crystal System is orthorhombic. Crystal Habits include fibrous, acicular and prismatic habits, but more commonly found as tabular, somewhat elongated crystals and aggregate spherulites.
Fracture is splintery to uneven.
Hardness is 6 - 7. Streak is white. Associated Minerals are many and include nepheline , aegirine , pyrite , sphalerite , serandite , eudialyte , catapleiite , elpidite , pyrophanite , astrophyllite , molybdenite , natrolite , siderite , rhodochrosite , calcite , analcime , feldspars , micas and fluorite . Best Field Indicators are crystal habit, cleavage, associations, locality and hardness.