metamorphic
Quartz Veined Mudstone
Metasedimentary rock with Quartz (SiO2) veins
Hardness: 7 (veins) to 5.5 (host rock). Color: Grey, tan, and white. Luster: Vitreous to dull. Cleavage: Indistinct. The specimen shows secondary mineral precipitation (quartz) within fractures of a sedimentary or low-grade metamorphic host.
- Hardness
- 7 (veins) to 5
- Color
- Grey, tan, and white
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (veins) to 5.5 (host rock). Color: Grey, tan, and white. Luster: Vitreous to dull. Cleavage: Indistinct. The specimen shows secondary mineral precipitation (quartz) within fractures of a sedimentary or low-grade metamorphic host.
Formation & geological history
Formed when hydrothermal fluids rich in silica injected into fractures of a pre-existing mudstone or siltstone under heat and pressure, typically during mountain-building events.
Uses & applications
Landscaping, educational specimens, and rough material for amateur lapidary work. Most valuable for teaching geological structural processes.
Geological facts
The white bands indicate 'crack-seal' events where the rock literally split open and was 'healed' by mineral growth from circulating groundwater multiple times.
Field identification & locations
Identify by the distinct white crystalline bands cutting through a darker, finer-grained matrix. Often found in riverbeds or areas with significant tectonic history.
