Geology Home Page
Roger Weller, geology instructor
Chemical Group: oxide
Chemical Formula: SnO2
Color: yellow, red-brown, brown-black
Streak: white, grayish, brownish
Hardness: 6 to 7
Specific Gravity: 6.8 to 7.1
Fracture: subconchoidal to uneven
Cleavage: 2 directions, one perfect and the other imperfect
Crystal Forms and Habits:
Cassiterite commonly forms twinned crystals (contact and penetration twins).
Crystals may also be needle-like.
In massive form, occurs in botryoidal nodules with concentric banding (wood tin).
Identifying Characteristics: high specific gravity and hardness
Uses: tin ore
Toxicity: when-swallowed- low when inhaled- moderate