Yellow glass (cullet/slag glass)
mineral · common
Quick facts
- Formula
- Non‑crystalline SiO2 with modifiers (e.g., Na2O, CaO, K2O) and colorants
- Hardness
- about 5–6 (typically ~5.5)
- Luster
- vitreous
- Colors
- colorless to any color depending on additives; here bright yellow
Man‑made glass forms when a silicate melt is cooled fast enough to prevent crystals from growing. Decorative cullet or 'slag glass' often enters rock collections and can closely mimic natural minerals.
Uniform color, flow lines and spherical bubbles, very sharp conchoidal fracture with no cleavage, isotropic optics, and hardness lower than quartz.
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