How to identify Moss Agate
Silicon dioxide (SiO2) with inclusions of chlorite, hornblende, or manganese oxides
Got a photo? Identify rocks instantly with the Rockby app
Open the appTo correctly identify Moss Agate (Silicon dioxide (SiO2) with inclusions of chlorite, hornblende, or manganese oxides), check each of these features in order. Many rocks and minerals look alike, so cross-reference multiple properties before deciding.
Step-by-step identification
- 1
Color
Overall color and any zoning or banding
Translucent to opaque base of colorless, white, gray, or bluish chalcedony with green, black, brown, or reddish dendritic inclusions.
- 2
Luster
How the surface reflects light: metallic, vitreous, dull
Vitreous to waxy.
- 3
Texture
Grain size and surface feel: coarse, fine, glassy
Smooth to slightly granular when unpolished; conchoidal fracture surfaces are smooth.
- 4
Crystal Form
Shape of visible crystals or crystal faces
Cryptocrystalline aggregates, typically massive, botryoidal, or stalactitic forms filling veins and cavities.
- 5
Cleavage
How it breaks: flat cleavage planes vs irregular fracture
None, due to its cryptocrystalline nature.
- 6
Geological Environment
The rock formation and setting where it occurs
Hydrothermal veins and amygdules in volcanic rocks (e.g., basalts, andesites), and sometimes in sedimentary rocks where silica-rich fluids have permeated.
Key Facts
- Hardness
- 6.5-7 on the Mohs scale (due to chalcedony).
- Specific Gravity
- 2.58-2.64.
- Crystal System
- Trigonal (for the constituent quartz microcrystals).
- Color
- Colorless, white, gray, or bluish base with green, black, brown, or reddish inclusions.
- Luster
- Vitreous to waxy.
- Transparency
- Translucent to opaque.
- Fracture
- Conchoidal.
- Cleavage
- None.
- Composition
- Silicon dioxide (SiO2) with inclusions of chlorite, hornblende, manganese oxides, or iron oxides.
Physical characteristics
- Crystal Habit: Cryptocrystalline, massive, botryoidal, stalactitic, nodular, or filling veins and amygdules.
- Cleavage Type: None.
- Fracture Type: Conchoidal.
- Tenacity: Brittle.
- Luster Type: Vitreous to waxy.
Explore Moss Agate
Identify rocks anywhere
Free on iOS, Android, and Web. Photo identification, full database, and your personal collection.