Definition
Rhyolite is a fine-grained igneous rock which is rich in silica
Tephrite is an aphanitic to porphyritic textured, volcanic igneous rock
Origin
North America
Germany
Discoverer
Ferdinand von Richthofen
Van Tooren
Etymology
From German Rhyolit, from Greek rhuax lava stream + lithos stone
From Greek tephra, ashes from Indo-European base, to burn
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Other Categories
Coarse Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Aphanitic, Glassy, Porphyritic
Aphanitic to Porphyritic
Color
Grey, White, Light Black
Black, Brown, Green, Grey, White
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Banded
Vesicular
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, 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
Landscaping
Antiquity Uses
Artifacts
Artifacts, Sculpture
Commercial Uses
Gemstone, Laboratory bench tops, Jewelry
Production of Lime, Soil Conditioner
Types
Pumice Rocks, Obsidian Rocks, Perlite Rocks, Porphyritic Rocks.
Igneous rock
Features
Acidic in nature, Available in lots of colors
Host Rock for Lead
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.
Tephrite 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.
Mineral Content
Biotite, Feldspar, Hornblade, Plagioclase, Pyroxene, Quartz
Alkali feldspar, Nepheline, Plagioclase, Pyroxene
Compound Content
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide, Sodium
CaO, Carbon Dioxide, MgO, Silicon Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
Cataclastic Metamorphism, Contact Metamorphism, Impact 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
Grain Size
Large and Coarse Grained
Medium to Fine Coarse Grained
Fracture
Sub-conchoidal
Uneven
Porosity
Highly Porous
Very Less Porous
Luster
Earthy
Subvitreous to Dull
Cleavage
-
Crenulation and Pervasive
Specific Gravity
2.65-2.67
2.86
Transparency
Opaque
Opaque
Density
2.4-2.6 g/cm3
2.8-2.9 g/cm3
Resistance
Heat Resistant, Wear Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Africa
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
Namibia, Uganda
Europe
Germany, Iceland, Ireland, Italy, Spain
Germany, Hungary, Italy, Portugal, Spain
Deposits in Western Continents
North America
Canada, USA
USA
South America
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
-
Deposits in Oceania Continent
Australia
New Zealand, Queensland, Western Australia
New Zealand, Western Australia