Definition
Comendite is a hard, peralkaline igneous rock, a type of light blue grey rhyolite
Rhyodacite is an extrusive volcanic rock intermediate in composition between dacite and rhyolite
Discoverer
Unknown
Unknown
Etymology
Comendite derives its name from the area of Le Commende on San Pietro Island in Italy
Rhyo lite + dacite : a rock intermediate between rhyolite and dacite that is the extrusive equivalent of granodiorite
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Other Categories
Medium Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Porphyritic
Earthy
Color
Blue, Bluish - Grey
Black to Grey, Dark Greenish - Grey
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Foliated
Skeletal
Interior Uses
Countertops, Decorative Aggregates, Interior Decoration
Decorative Aggregates, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration
As Building Stone, Garden Decoration
Other Architectural Uses
Curbing
Curbing
Construction Industry
Building houses or walls, Cement Manufacture, Construction Aggregate, for Road Aggregate, Landscaping, Making natural cement, Raw material for the manufacture of mortar
As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping
Antiquity Uses
Artifacts
Artifacts
Commercial Uses
Cemetery Markers
Cemetery Markers, Creating Artwork
Types
Rhyolite
Intermediate volcanic rock
Features
Very fine grained rock, It is One of the Oldest, Strongest and Hardest Rock
Available in Lots of Colors and Patterns
Archaeological Significance
Formation
Comendite is a type of Igneous rock which is formed due to cooling and solidification of lava or magma. It may form with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.
Rhyodacite is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.
Mineral Content
Albite, Amphibole, Quartz
Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon
Compound Content
Al, Fe, Potassium Oxide
Ca, Fe, Potassium Oxide, Potassium, Silicon Dioxide
Types of Metamorphism
Cataclastic Metamorphism, Regional Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Coastal Erosion, Water Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Grain Size
Medium Grained
Fine Grained
Fracture
Pervasive
Conchoidal
Streak
Bluish Black
Black
Porosity
Highly Porous
Less Porous
Luster
Dull
Greasy to Dull
Specific Gravity
2.38
2.34-2.40
Transparency
Opaque
Opaque
Density
-9999 g/cm3
-9999 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant
Deposits in Eastern Continents
Asia
China
China, India, Iran, Saudi Arabia, Sri Lanka, Taiwan, Thailand, Turkey, Vietnam
Africa
East Africa
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
Europe
Italy
Austria, Belgium, Finland, France, Germany, Italy, Norway, Sardinia, Spain, Switzerland
Deposits in Western Continents
North America
-
Canada, USA
Deposits in Oceania Continent