Rhyolite and Dacite
Definition
Definition
Rhyolite is a fine-grained igneous rock which is rich in silica
Dacite is a volcanic igneous rock which is rintermediate in composition between andesite and rhyolite
History
Origin
North America
Romania and Moldova, Europe
Discoverer
Ferdinand von Richthofen
Unknown
Etymology
From German Rhyolit, from Greek rhuax lava stream + lithos stone
From Dacia, a province of the Roman Empire which lay between the Danube River and Carpathian Mountains where the rock was first described
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Soft Rock
Family
Group
Volcanic
Volcanic
Other Categories
Coarse Grained Rock, Opaque Rock
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Texture
Aphanitic, Glassy, Porphyritic
Aphanitic to Porphyritic
Color
Grey, White, Light Black
Bluish - Grey, Brown, Grey, Light to Dark Grey
Maintenance
More
Less
Durability
Durable
Durable
Water Resistant
Yes
No
Scratch Resistant
Yes
No
Stain Resistant
Yes
No
Wind Resistant
Yes
No
Acid Resistant
Yes
No
Appearance
Banded
Vesicular
Uses
Architecture
Interior Uses
Decorative Aggregates, Homes, Hotels, Interior Decoration, Kitchens
Decorative Aggregates, Entryways, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Paving Stone, Office Buildings
As Building Stone, Paving Stone, Garden Decoration
Other Architectural Uses
Not Yet Used
Curbing
Industry
Construction Industry
Arrowheads, As Dimension Stone, Building houses or walls, Construction Aggregate, Cutting Tool, for Road Aggregate, Knives
As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts
Artifacts
Other Uses
Commercial Uses
Gemstone, Laboratory bench tops, Jewelry
Commemorative Tablets, Creating Artwork
Types
Types
Pumice Rocks, Obsidian Rocks, Perlite Rocks, Porphyritic Rocks.
Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite
Features
Acidic in nature, Available in lots of colors
Host Rock for Lead, 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
Not Used
Used
Petroglyphs
Not Used
Used
Figurines
Not Yet Used
Not Yet Used
Fossils
Absent
Absent
Formation
Formation
Rhyolite is a felsic extrusive rock and due to its high silica content, rhyolite lava is very viscous and is volcanic equivalent of granite.
Dacitic magma is formed by the subduction of young oceanic crust under a thick felsic continental plate. Further, the Oceanic crust is hydrothermally altered as quartz and sodium are added.
Composition
Mineral Content
Biotite, Feldspar, Hornblade, Plagioclase, Pyroxene, Quartz
Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon
Compound Content
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide, Sodium
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide
Transformation
Metamorphism
Yes
Yes
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
Burial Metamorphism, Cataclastic Metamorphism
Weathering
Yes
Yes
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
Yes
Yes
Types of Erosion
Chemical Erosion, Sea Erosion, Water Erosion, Wind Erosion
Chemical Erosion
Properties
Physical Properties
Hardness
6-7
2-2.25
Grain Size
Large and Coarse Grained
Medium to Fine Coarse Grained
Fracture
Sub-conchoidal
Conchoidal
Streak
Colorless
White
Porosity
Highly Porous
Less Porous
Luster
Earthy
Subvitreous to Dull
Compressive Strength
140.00 N/mm2
15
Not Available
Cleavage
Not Available
Perfect
Toughness
2
Not Available
Specific Gravity
2.65-2.67
2.86-2.87
Transparency
Opaque
Translucent
Density
2.4-2.6 g/cm3
2.77-2.771 g/cm3
Thermal Properties
Specific Heat Capacity
Not Available
0.92 kJ/Kg K
10
Resistance
Heat Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Reserves
Deposits in Eastern Continents
Asia
China, India
Not Yet Found
Africa
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
Not Yet Found
Europe
Germany, Iceland, Ireland, Italy, Spain
France, Greece, Romania, Scotland, Spain
Others
Not Yet Found
Not Yet Found
Deposits in Western Continents
North America
Canada, USA
USA
South America
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
New Zealand, Queensland, Western Australia
New Zealand, South Australia, Western Australia
All about Rhyolite and Dacite Properties
Know all about Rhyolite and Dacite properties here. All properties of rocks are important as they define the type of rock and its application. Rhyolite and Dacite belong to Igneous Rocks.Texture of Rhyolite is Aphanitic, Glassy, Porphyritic whereas that of Dacite is Aphanitic to Porphyritic. Rhyolite appears Banded and Dacite appears Vesicular. The luster of Rhyolite is earthy while that of Dacite is subvitreous to dull. Rhyolite is available in grey, white, light black colors whereas Dacite is available in bluish - grey, brown, grey, light to dark grey colors. The commercial uses of Rhyolite are gemstone, laboratory bench tops, jewelry and that of Dacite are commemorative tablets, creating artwork.
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