Definition
Rhyolite is a fine-grained igneous rock which is rich in silica
Trachyte is a grey fine-grained volcanic rock which mainly consists of alkali feldspar
Discoverer
Ferdinand von Richthofen
Alexandre Brongniart and René Just Haüy
Etymology
From German Rhyolit, from Greek rhuax lava stream + lithos stone
From Greek trakhus rough’ or trakhutēs roughness
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Other Categories
Coarse Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Aphanitic, Glassy, Porphyritic
Aphanitic to Porphyritic
Color
Grey, White, Light Black
Black, Brown, Dark Greenish - Grey, Green, Grey, Light to Dark Grey, White
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Interior Uses
Decorative Aggregates, Homes, Hotels, Interior Decoration, Kitchens
Decorative Aggregates, Flooring, Homes, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Paving Stone, Office Buildings
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration, Office Buildings
Other Architectural Uses
-
Curbing
Construction Industry
Arrowheads, As Dimension Stone, Building houses or walls, Construction Aggregate, Cutting Tool, for Road Aggregate, Knives
As Dimension Stone, Building houses or walls, Cement Manufacture, Construction Aggregate, for Road Aggregate, Landscaping, Making natural cement, Manufacture of Magnesium and Dolomite Refractories
Antiquity Uses
Artifacts
Artifacts, Monuments, Sculpture, Small Figurines
Commercial Uses
Gemstone, Laboratory bench tops, Jewelry
Cemetery Markers, Creating Artwork
Types
Pumice Rocks, Obsidian Rocks, Perlite Rocks, Porphyritic Rocks.
Felsic volcanic rock
Features
Acidic in nature, Available in lots of colors
Available in Lots of Colors and Patterns, Is one of the oldest rock, Matrix variable
Archaeological Significance
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.
Trachyte is an igneous volcanic rock with an aphanitic to porphyritic texture. It is the volcanic equivalent of syenite rock and forms as a result of magmatic differentiation.
Mineral Content
Biotite, Feldspar, Hornblade, Plagioclase, Pyroxene, Quartz
Augite, Biotite, Feldspar, Hornblade, Plagioclase, Quartz
Compound Content
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide, Sodium
Potassium Oxide, Sodium Oxide, Silicon Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
Cataclastic Metamorphism, Contact Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Sea Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Grain Size
Large and Coarse Grained
Fine Grained
Fracture
Sub-conchoidal
-
Porosity
Highly Porous
Less Porous
Specific Gravity
2.65-2.67
2.7
Transparency
Opaque
Opaque
Density
2.4-2.6 g/cm3
2.43-2.45 g/cm3
Resistance
Heat Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
China, India
China, India, Iran, Saudi Arabia, Sri Lanka, Taiwan, Thailand, Turkey, Vietnam
Africa
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
Europe
Germany, Iceland, Ireland, Italy, Spain
Bulgaria, England, Germany, Norway, Romania, Switzerland
Deposits in Western Continents
North America
Canada, USA
USA
South America
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Brazil, Chile
Deposits in Oceania Continent
Australia
New Zealand, Queensland, Western Australia
New Zealand, Queensland, South Australia, Western Australia