Bloodstone, agate, and onyx are chalcedonic varieties of this mineral.  Other color variations arise
Bloodstone, agate, and onyx are chalcedonic varieties of this mineral.  Other color variations arise from substituting atoms for silicon; iron for citrine and amethysts, titanium for the rose variety.  When cemented it makes sandstone and when fused, silica glass.  For ten points, identify this mineral composed of crystalline silicon dioxide.
Bloodstone, agate, and onyx are chalcedonic varieties of this mineral.  
quartz