Purple Agate (Dyed Chalcedony)

Physical Properties

Hardness: 6.5-7 on the Mohs scale. Color: Naturally gray, white, or blue, but dyed deep purple in this specimen. Luster: Waxy to vitreous. Crystal structure: Trigonal/Microcrystalline. Cleavage: None. Specific gravity: 2.58–2.64.

Formation & Geological History

Formed primarily within volcanic and metamorphic rocks. Agates develop as silica-rich groundwater fills cavities (vesicles) in cooling lava. Most vibrant purple colors seen in commercial tumbled stones are achieved through artificial dyeing processes after mining.

Uses & Applications

Used extensively in jewelry (beads, cabochons), decorative ornaments, bookends, and as healing stones in metaphysical practices. Industrially used for precision pendulums and laboratory mortars/pestles due to its hardness.

Geological Facts

Agate was named by the Greek philosopher Theophrastus, who discovered the stone along the shorelines of the Achates River in Sicily. While natural purple agate exists, it is extremely rare and usually a very pale lavender; deep indigo or violet specimens are almost always enhanced.

Field Identification & Locations

Identify by its translucent quality and characteristic concentric banding (seen clearly in the lower half of this specimen). In the field, look for nodules with a waxy exterior in riverbeds or volcanic ash deposits. Common in Brazil, Uruguay, and the United States (Lake Superior region).

Identified on: 4/22/2026

Mode: Standard