Definition
Rhyodacite is an extrusive volcanic rock intermediate in composition between dacite and rhyolite
Nephelinite is a fine-grained or aphanitic igneous rock made up almost entirely of nepheline and clinopyroxene (variety augite).
Discoverer
Unknown
Unknown
Etymology
Rhyo lite + dacite : a rock intermediate between rhyolite and dacite that is the extrusive equivalent of granodiorite
from French néphéline, from Greek nephelē
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Color
Black to Grey, Dark Greenish - Grey
Black, Brown, Colourless, Green, Grey, White
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Skeletal
Skeletal
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Homes, Interior Decoration
Exterior Uses
As Building Stone, Garden Decoration
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
Other Architectural Uses
Curbing
Curbing
Construction Industry
As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts
Artifacts, Monuments, Sculpture, Small Figurines
Commercial Uses
Cemetery Markers, Creating Artwork
Creating Artwork, Soil Conditioner, Source of Magnesia (MgO)
Types
Not Available
Peralkaline Nephelinite
Features
Available in Lots of Colors and Patterns
Host Rock for Lead
Archaeological Significance
Monuments
Not Yet Used
Used
Famous Monuments
Not Applicable
Data Not Available
Sculpture
Not Yet Used
Used
Famous Sculptures
Not Applicable
Data Not Available
Pictographs
Used
Not Used
Petroglyphs
Used
Not Used
Figurines
Not Yet Used
Used
Formation
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.
Nephelinite 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
Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon
Clinopyroxene, Nepheline, Plagioclase
Compound Content
Ca, Fe, Potassium Oxide, NA, Potassium, Silicon Dioxide
Ca, CaO, Carbon, Cl, MgO
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Contact Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Chemical Erosion, Water Erosion, Wind Erosion
Grain Size
Fine Grained
Fine Grained
Porosity
Less Porous
Less Porous
Luster
Greasy to Dull
Vitreous to Metallic
Cleavage
Not Available
Imperfect
Specific Gravity
2.34-2.40
2.4-2.9
Transparency
Opaque
Opaque
Density
Not Available
2.5-3 g/cm3
Resistance
Heat Resistant
Heat Resistant
Deposits in Eastern Continents
Asia
China, India, Iran, Saudi Arabia, Sri Lanka, Taiwan, Thailand, Turkey, Vietnam
Japan
Africa
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
Rwanda, Tanzania
Europe
Austria, Belgium, Finland, France, Germany, Italy, Norway, Sardinia, Spain, Switzerland
Not Yet Found
Others
Not Yet Found
Hawaii Islands
Deposits in Western Continents
North America
Canada, USA
Canada, USA
South America
Not Yet Found
Colombia
Deposits in Oceania Continent
Australia
Not Yet Found
Not Yet Found