sedimentary
Wishing Stone (Graywacke with Quartz Vein)
Graywacke Sandstone containing a Quartz (SiO2) intrusion
Hardness: 6.5-7 (Mohs scale); Color: Dark gray/greenish base with a white or cream stripe; Luster: Dull/earthy (matrix), vitreous (vein); Texture: Fine-grained clastic; Cleavage: None.
- Hardness
- 6
- Color
- Dark gray/greenish base with a white or cream stripe
- Luster
- Dull/earthy (matrix), vitreous (vein)
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Dark gray/greenish base with a white or cream stripe; Luster: Dull/earthy (matrix), vitreous (vein); Texture: Fine-grained clastic; Cleavage: None.
Formation & geological history
Formed from the rapid deposition of muddy sand in deep ocean environments (turbidites). The white line is a hydrothermal vein formed when mineral-rich water filled a crack in the rock and crystallized over millions of years.
Uses & applications
Commonly used as a decorative pocket stone or garden rock; historically used in construction and road base due to its extreme hardness and durability.
Geological facts
In folklore, these are called 'Wishing Stones.' To make a wish, you must find one with a single continuous white line that circles the entire rock without breaking.
Field identification & locations
Identify by looking for a smooth, water-worn cobble with a distinct, single white stripe. Most commonly found on beaches or in riverbeds where glacial or water erosion has polished the surface.
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