mineral

Agate Geode Node

Cryptocrystalline Quartz (SiO2)

Hardness: 6.5-7 on Mohs scale. Color: Gray, tan, white, and earthy brown banding. Luster: Waxy to vitreous. Crystal structure: Hexagonal (microcrystalline). Cleavage: None (conchoidal fracture). Specific gravity: 2.6.

Hardness: 6
Color: Gray, tan, white, and earthy brown banding
Luster: Waxy to vitreous

Identified March 12, 2026More mineral →

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Physical properties

Formation & geological history

Formed in cavities (vesicles) within igneous volcanic rocks, such as basalt or rhyolite, through the deposition of silica-rich groundwater. Over millions of years, multiple layers deposit to create the characteristic banding. Ages vary from 30 million to over 1 billion years depending on location.

Uses & applications

Commonly used for lapidary work, jewelry (beads/cabochons), paperweights, and as metaphysical or display specimens for collectors.

Geological facts

Agate is a variety of chalcedony. The hollow center of this specimen, if lined with crystals, makes it a geode; if solid, it is often called an agate nodule. The banding is caused by variations in the mineral impurities during deposition.

Field identification & locations

Identify by its distinct concentric banding and smooth, waxy surface when broken. In the field, look for rounded, cauliflower-like exterior textures on heavy rocks. Found globally in hotbeds like Brazil, Uruguay, and the Lake Superior region of the USA.