Manufacturers added manganese oxide to "mask" the natural green or aqua tint caused by iron impurities in the sand used for glassmaking.
Beverage and medicine bottles are the most common finds. Tableware: Pressed glass dishes and decorative items. Colored Amethyst
When exposed to sunlight (UV radiation), the manganese undergoes a chemical change, shifting the glass from clear to various shades of amethyst or violet. 2. Archaeological Significance Manufacturers added manganese oxide to "mask" the natural
The purplish hue is the result of a specific manufacturing process: the manganese undergoes a chemical change