Montana Moss Agate
A variety of Chalcedony
What is Montana Moss Agate?
Montana Moss Agate is a Moss Agate found exclusively in the alluvial gravels of the Yellowstone River (Montana, USA). This semi-precious stone is mostly yellow or white, with prominent, dark, tree-like or moss-like markings. The attractive and unusual appearance is a result of volcanic activities and lava flows in Yellowstone National Park.
Optical Properties
- Refractive Index
- 1.530-1.543
- Birefringence
- 0.003-0.009
- Pleochroism
- None
- Optical Character
- Biaxial positive
- Dispersion
- 0.013
Discover Values
This stone excels in beauty.
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Montana Moss Agate Localities Map
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Key Characteristics
Formation of Montana Moss Agate
It was originally formed in the Yellowstone National Park area of Wyoming as a result of volcanic activity.
Health & Safety Information
- ⚠️Harm Reason: Montana Moss Agate in powdered form can be toxic due to its Crystalline Silica content.
- ⚠️Physical Toxicity: Quartz, silica, crystalline silica and flint are non-toxic materials, but very fine dust containing quartz, known as respirable crystalline silicon (RCS), can cause serious and fatal lung disease. Lapidaries should exercise caution when cutting silica.
- ⚠️How to prevent the risks of Montana Moss Agate?
Quick Facts
Physical Properties
- Color
- Gray, white, brown, black, red, orange, yellow
- Hardness (Mohs)
- 6.5 - 7
- Density
- 2.55 - 2.7 g/cm³
- Streak
- Green
- Luster
- Waxy, Vitreous
- Crystal System
- Trigonal
Chemical Properties
- Chemical Formula
- SiO2
- Elements
- Si, O
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