Definition
Rhyodacite is an extrusive volcanic rock intermediate in composition between dacite and rhyolite
Appinite is an igneous rock in which the crystals are so fine grained that individual minerals cannot be easily distinguished
Discoverer
Unknown
Unknown
Etymology
Rhyo lite + dacite : a rock intermediate between rhyolite and dacite that is the extrusive equivalent of granodiorite
From the variety of Lamprophyre Greek lampros bright and shining + porphureos purple
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Opaque Rock
Texture
Earthy
Porphyritic
Color
Black to Grey, Dark Greenish - Grey
Black, Bluish - Grey, Brown, Dark Greenish - Grey, Green, Grey
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Skeletal
Dull, Banded and Foilated
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Homes, Interior Decoration
Exterior Uses
As Building Stone, Garden Decoration
Paving Stone, Garden Decoration, Office Buildings
Other Architectural Uses
Curbing
Whetstones
Construction Industry
As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping
As Dimension Stone, Cement Manufacture, for Road Aggregate, Making natural cement, Manufacture of Magnesium and Dolomite Refractories
Medical Industry
Not Yet Used
Taken as a Supplement for Calcium or Magnesium
Antiquity Uses
Artifacts
Artifacts, Monuments, Sculpture, Small Figurines
Commercial Uses
Cemetery Markers, Creating Artwork
An Oil and Gas Reservoir, As a Feed Additive for Livestock, Gemstone, Metallurgical Flux, Production of Lime, Soil Conditioner
Types
Not Available
Not Available
Features
Available in Lots of Colors and Patterns
Always found as volcanic pipes over deep continental crust, Host rock for Diamond, Is one of the oldest rock, Surfaces are often shiny
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
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.
The formation of Appinite takes place deep beneath the Earth’s surface at around 150 to 450 kms, and are erupted rapidly and violently.
Mineral Content
Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon
Amphibole, Carbonate, Garnet, Micas, Olivine, Phlogopite, Pyroxene
Compound Content
Ca, Fe, Potassium Oxide, NA, Potassium, Silicon Dioxide
Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical 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 to Coarse Grained
Fracture
Conchoidal
Conchoidal
Porosity
Less Porous
Very Less Porous
Luster
Greasy to Dull
Subvitreous to Dull
Compressive Strength
Not Available
Cleavage
Not Available
Conchoidal
Toughness
2.1
Not Available
Specific Gravity
2.34-2.40
2.86-2.87
Transparency
Opaque
Translucent to Opaque
Density
Not Available
2.95-2.96 g/cm3
Specific Heat Capacity
Not Available
Resistance
Heat Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
China, India, Iran, Saudi Arabia, Sri Lanka, Taiwan, Thailand, Turkey, Vietnam
Russia
Africa
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
Angola, Botswana, Cameroon, Ethiopia, South Africa
Europe
Austria, Belgium, Finland, France, Germany, Italy, Norway, Sardinia, Spain, Switzerland
England, Hungary, Iceland, United Kingdom
Others
Not Yet Found
Antarctica, Greenland
Deposits in Western Continents
North America
Canada, USA
Canada, Mexico, USA
South America
Not Yet Found
Argentina, Colombia, Ecuador
Deposits in Oceania Continent
Australia
Not Yet Found
New South Wales, New Zealand, Queensland, South Australia, Western Australia