Definition
Rhyodacite is an extrusive volcanic rock intermediate in composition between dacite and rhyolite
Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture
Discoverer
Unknown
Unknown
Etymology
Rhyo lite + dacite : a rock intermediate between rhyolite and dacite that is the extrusive equivalent of granodiorite
From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Group
Volcanic
Not Applicable
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Earthy
Banded, Rough
Color
Black to Grey, Dark Greenish - Grey
Black, Brown, Green, Grey, Red, White
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Skeletal
Glassy or Pearly
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Homes
Exterior Uses
As Building Stone, Garden Decoration
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings
Other Architectural Uses
Curbing
Curbing
Construction Industry
As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping
Arrowheads, Construction Aggregate, Cutting Tool, Spear Points
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts
Artifacts, Monuments
Commercial Uses
Cemetery Markers, Creating Artwork
Creating Artwork, Gemstone, In fire-starting tools, Jewelry, To ignite fire, Used in flintlock firearms
Types
Not Available
Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter
Features
Available in Lots of Colors and Patterns
Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate
Archaeological Significance
Monuments
Not Yet Used
Used
Famous Monuments
Not Applicable
Data Not Available
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.
Chert forms when microcrystals of silicon dioxide grow within soft sediments that become limestone or chalk. The chert formation can be either of chemical or biological origin.
Mineral Content
Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon
Quartz, Silicon
Compound Content
Ca, Fe, Potassium Oxide, NA, Potassium, Silicon Dioxide
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
Not Applicable
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Chemical Erosion
Grain Size
Fine Grained
Very fine-grained
Fracture
Conchoidal
Uneven, Splintery or Conchoidal
Porosity
Less Porous
Highly Porous
Luster
Greasy to Dull
Waxy and Dull
Cleavage
Not Available
Non-Existent
Specific Gravity
2.34-2.40
2.5-2.8
Transparency
Opaque
Translucent to Opaque
Density
Not Available
2.7 g/cm3
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, Japan, 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
Rhyodacite vs Chert Characteristics
Though some rocks look identical, they have certain characteristics which distinguish them from others. Characteristics of rocks include texture, appearance, color, fracture, streak, hardness etc. Rhyodacite vs Chert characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Rhyodacite and Properties of Chert. Learn more about Rhyodacite vs Chert in the next section. The interior uses of Rhyodacite include Decorative aggregates and Interior decoration whereas the interior uses of Chert include Decorative aggregates and Homes. Due to some exceptional properties of Rhyodacite and Chert, they have various applications in construction industry. The uses of Rhyodacite in construction industry include As dimension stone, Construction aggregate, For road aggregate, Landscaping and that of Chert include Arrowheads, Construction aggregate, Cutting tool, Spear points.
More about Rhyodacite and Chert
Here you can know more about Rhyodacite and Chert. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Rhyodacite and Chert consists of mineral content and compound content. The mineral content of Rhyodacite includes Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon and mineral content of Chert includes Quartz, Silicon. You can also check out the list of all Igneous Rocks. When we have to compare Rhyodacite vs Chert, the texture, color and appearance plays an important role in determining the type of rock. Rhyodacite is available in black to grey, dark greenish - grey colors whereas, Chert is available in black, brown, green, grey, red, white colors. Appearance of Rhyodacite is Skeletal and that of Chert is Glassy or Pearly. Properties of rock is another aspect for Rhyodacite vs Chert. The hardness of Rhyodacite is 5.5-6 and that of Chert is 6.5-7. The types of Rhyodacite are Not Available whereas types of Chert are Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Rhyodacite is black while that of Chert is white. The specific heat capacity of Rhyodacite is 1.12 kJ/Kg K and that of Chert is 0.74 kJ/Kg K. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Rhyodacite is heat resistant whereas Chert is heat resistant, impact resistant, pressure resistant, wear resistant.