Chalcedony (Micro/Cryptocrystalline Quartz)SiO2
Class: Silicate Subclass: Framework Hardness: 7 Density: 2.7 Streak: White Lustre: Vitreous / almost waxy Habit: Aggregate of very tiny SiO2 grains. Colours: White/gray or any colour | | Crystal System: Hexagonal Cleavage: None Fracture: Conchoidal Magnetism: None Reaction with HCl: None | Identification in hand sample: Identified by hardness and texture/habit. Associations: Abundant in felsic rocks. Industrial / ecomonic uses: Used for making glass and as a source of Silicon. |