Definition
Rhyodacite is an extrusive volcanic rock intermediate in composition between dacite and rhyolite
Banded iron formation are distinctive units of sedimentary rock that are almost always of Precambrian age
Origin
USA
Western Australia, Minnesota
Discoverer
Unknown
Unknown
Etymology
Rhyo lite + dacite : a rock intermediate between rhyolite and dacite that is the extrusive equivalent of granodiorite
From its formation process
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
Group
Volcanic
Not Applicable
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock
Texture
Earthy
Banded, Trellis
Color
Black to Grey, Dark Greenish - Grey
Red, Reddish Brown
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Skeletal
Layered, Banded, Veined and Shiny
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Homes
Exterior Uses
As Building Stone, Garden Decoration
Paving Stone, Office Buildings
Other Architectural Uses
Curbing
Curbing, Whetstones
Construction Industry
As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping
As Dimension Stone, Used for flooring, stair treads, borders and window sills.
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts
Artifacts
Commercial Uses
Cemetery Markers, Creating Artwork
As a touchstone, Cemetery Markers, Creating Artwork
Types
Not Available
Algoma-type , Lake Superior-type, Superior-type and Taconite
Features
Available in Lots of Colors and Patterns
Is one of the oldest rock
Archaeological Significance
Monuments
Not Yet Used
Not Yet Used
Famous Monuments
Not Applicable
Not Applicable
Sculpture
Not Yet Used
Not Yet Used
Famous Sculptures
Not Applicable
Not Applicable
Pictographs
Used
Not Used
Petroglyphs
Used
Not Used
Figurines
Not Yet Used
Not Yet 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 banded iron layers are formed in sea water when oxygen is released by photosynthetic cyano-bacteria. The oxygen then combines with dissolved iron in ocean to form insoluble iron oxides, which precipitated out, forming a thin layer of banded iron formation on ocean floor.
Mineral Content
Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon
Hematite, Magnetite, Quartz
Compound Content
Ca, Fe, Potassium Oxide, NA, Potassium, Silicon Dioxide
Fe, Iron(III) Oxide, Silicon Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Not Applicable
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Chemical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Coastal Erosion, Wind Erosion
Grain Size
Fine Grained
Large and Coarse Grained
Fracture
Conchoidal
Uneven, Splintery or Conchoidal
Porosity
Less Porous
Highly Porous
Luster
Greasy to Dull
Earthy
Compressive Strength
Not Available
Cleavage
Not Available
Imperfect
Specific Gravity
2.34-2.40
5.0-5.3
Transparency
Opaque
Translucent to Opaque
Density
Not Available
Not Available
Resistance
Heat Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
China, India, Iran, Saudi Arabia, Sri Lanka, Taiwan, Thailand, Turkey, Vietnam
China, India, Iran, Iraq, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
Africa
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
Kenya, Morocco, South Africa, Tanzania
Europe
Austria, Belgium, Finland, France, Germany, Italy, Norway, Sardinia, Spain, Switzerland
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
Others
Not Yet Found
Greenland, Mid-Atlantic Ridge
Deposits in Western Continents
North America
Canada, USA
Canada, Mexico, USA
South America
Not Yet Found
Bolivia, Brazil
Deposits in Oceania Continent
Australia
Not Yet Found
New South Wales, Queensland, South Australia, Western Australia