Around the start of World War I, the supply of manganese (largely imported from Germany) was cut off. US manufacturers switched to selenium , which turns a straw or amber color when exposed to the sun, marking a distinct shift in the archaeological record. 3. Common Artifact Types Archaeologists frequently recover SCA in the form of:
Sun-colored amethyst refers to glass that has turned a purplish tint due to prolonged exposure to ultraviolet (UV) light. This phenomenon is not natural to the glass's original state but is a chemical reaction involving manganese oxide, which was used as a decolorizer in glass production between approximately . 1. Chemical Composition & Origin
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
The purplish hue is the result of a specific manufacturing process: Around the start of World War I, the
Because manganese was the primary decolorizer used specifically from 1890 to 1920 , the presence of SCA shards helps researchers pinpoint the age of a historical site.
This report examines glass, a specific type of historic artifact frequently used by archaeologists to date sites from the late 19th and early 20th centuries. Executive Summary Chemical Composition & Origin Beverage and medicine bottles
Manufacturers added manganese oxide to "mask" the natural green or aqua tint caused by iron impurities in the sand used for glassmaking.