mineral

Howlite and Tree Agate

Calcium Borosilicate Hydroxide (Howlite) and Silicon Dioxide (Agate/Quartz)

Howlite (white stone): Hardness 3.5, sub-vitreous to earthy luster, monoclinic system. Tree Agate (green/white stone): Hardness 6.5-7, vitreous luster, cryptocrystalline structure, dendritic green inclusions.

Identified July 5, 2026More mineral →

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Physical properties

Formation & geological history

Howlite forms in evaporite deposits. Tree Agate (a form of dendritic agate) forms through the cooling of silica-rich groundwater in rock cavities, with manganese or iron oxide forming the tree-like patterns.

Uses & applications

Commonly used for lapidary work, jewelry, pocket stones, decorative carvings, and as 'healing crystals' in metaphysical practices.

Geological facts

Howlite is naturally white but is the most common stone used to create 'imitation turquoise' by being dyed blue. Tree Agate is technically not a 'true' agate because it lacks banding, but it is a chalcedony with dendritic inclusions.

Field identification & locations

Identify Howlite by its white color and spider-web grey veins; it is much softer than quartz. Identify Tree Agate by its mossy or fern-like green patterns against a white/clear background. Often found in riverbeds or as tumbled stones.

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