Rhyolite and Obsidian
Definition
Definition
Rhyolite is a fine-grained igneous rock which is rich in silica
Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth
History
Origin
North America
Ethiopia
Discoverer
Ferdinand von Richthofen
Obsius
Etymology
From German Rhyolit, from Greek rhuax lava stream + lithos stone
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
Volcanic
Volcanic
Other Categories
Coarse Grained Rock, Opaque Rock
Opaque Rock
Texture
Texture
Aphanitic, Glassy, Porphyritic
Glassy
Color
Grey, White, Light Black
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Maintenance
More
Less
Durability
Durable
Durable
Water Resistant
Yes
Yes
Scratch Resistant
Yes
Yes
Stain Resistant
Yes
No
Wind Resistant
Yes
No
Acid Resistant
Yes
No
Appearance
Banded
Shiny
Uses
Architecture
Interior Uses
Decorative Aggregates, Homes, Hotels, Interior Decoration, Kitchens
Decorative Aggregates, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Paving Stone, Office Buildings
Garden Decoration
Other Architectural Uses
Not Yet Used
Not Yet Used
Industry
Construction Industry
Arrowheads, As Dimension Stone, Building houses or walls, Construction Aggregate, Cutting Tool, for Road Aggregate, Knives
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
Medical Industry
Not Yet Used
Surgery
Antiquity Uses
Artifacts
Artifacts, Jewellery
Other Uses
Commercial Uses
Gemstone, Laboratory bench tops, Jewelry
Creating Artwork, Mirror, Used in aquariums
Types
Types
Pumice Rocks, Obsidian Rocks, Perlite Rocks, Porphyritic Rocks.
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Features
Acidic in nature, Available in lots of colors
Blocks negativity, Helps to protect against depression
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.
When the lava is released from volcano, it undergoes a very rapid cooling which freezes the mechanisms of crystallization. The result is a volcanic glass with a uniform smooth texture.
Composition
Mineral Content
Biotite, Feldspar, Hornblade, Plagioclase, Pyroxene, Quartz
Not Available
Compound Content
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide, Sodium
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Transformation
Metamorphism
Yes
Yes
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact 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, Coastal Erosion, Glacier Erosion
Properties
Physical Properties
Hardness
6-7
5-5.5
Grain Size
Large and Coarse Grained
Not Applicable
Fracture
Sub-conchoidal
Conchoidal
Streak
Colorless
White
Porosity
Highly Porous
Very Less Porous
Luster
Earthy
Vitreous
Compressive Strength
140.00 N/mm2
15
0.15 N/mm2
33
Cleavage
Not Available
Non-Existent
Toughness
2
Not Available
Specific Gravity
2.65-2.67
2.6-2.7
Transparency
Opaque
Translucent
Density
2.4-2.6 g/cm3
2.6 g/cm3
Thermal Properties
Specific Heat Capacity
Not Available
0.92 kJ/Kg K
10
Resistance
Heat Resistant, Wear Resistant
Heat Resistant, Impact Resistant
Reserves
Deposits in Eastern Continents
Asia
China, India
Afghanistan, Indonesia, Japan, Russia
Africa
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
Kenya
Europe
Germany, Iceland, Ireland, Italy, Spain
Greece, Hungary, Iceland, Italy, Turkey
Others
Not Yet Found
Not Yet Found
Deposits in Western Continents
North America
Canada, USA
Canada, Mexico, USA
South America
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Argentina, Chile, Ecuador, Peru
Deposits in Oceania Continent
Australia
New Zealand, Queensland, Western Australia
New Zealand
All about Rhyolite and Obsidian Properties
Know all about Rhyolite and Obsidian properties here. All properties of rocks are important as they define the type of rock and its application. Rhyolite and Obsidian belong to Igneous Rocks.Texture of Rhyolite is Aphanitic, Glassy, Porphyritic whereas that of Obsidian is Glassy. Rhyolite appears Banded and Obsidian appears Shiny. The luster of Rhyolite is earthy while that of Obsidian is vitreous. Rhyolite is available in grey, white, light black colors whereas Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors. The commercial uses of Rhyolite are gemstone, laboratory bench tops, jewelry and that of Obsidian are creating artwork, mirror, used in aquariums.
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