Definition
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
Pantellerite is a peralkaline rhyolite. It has a higher iron and lower aluminium composition than comendite
History
Origin
Ethiopia
Strait of sicily
Discoverer
Obsius
Unknown
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From Pantelleria, a volcanic island in the Strait of Sicily
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Family
Group
Volcanic
Volcanic
Other Categories
Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Glassy
Eutaxitic
Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Dark Greenish - Grey
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Shiny
Layered and Foliated
Architecture
Interior Uses
Decorative Aggregates, Interior Decoration
-
Exterior Uses
Garden Decoration
-
Other Architectural Uses
-
-
Industry
Construction Industry
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
-
Medical Industry
Surgery
-
Antiquity Uses
Artifacts, Jewellery
Artifacts, Sculpture
Other Uses
Commercial Uses
Creating Artwork, Mirror, Used in aquariums
Creating Artwork
Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Pantelleritic Ignimbrite
Features
Blocks negativity, Helps to protect against depression
High Fe content
Archaeological Significance
Monuments
-
-
Famous Monuments
-
-
Sculpture
-
-
Famous Sculptures
-
-
Pictographs
-
-
Petroglyphs
-
-
Figurines
-
-
Fossils
Absent
Absent
Formation
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.
Pantellerite 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.
Composition
Mineral Content
-
Amphibole, Feldspar, Ilmenite
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Al, Fe
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Burial Metamorphism, Cataclastic Metamorphism
Weathering
✔
✘
✔
✘
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering
Erosion
✔
✘
✔
✘
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Physical Properties
Hardness
5-5.56-7
1
7
👆🏻
Grain Size
-
Fine Grained
Fracture
Conchoidal
Sub-conchoidal
Streak
White
-
Porosity
Very Less Porous
Less Porous
Luster
Vitreous
Earthy
Compressive Strength
0.15 N/mm2210.00 N/mm2
0.15
450
👆🏻
Cleavage
-
Conchoidal
Toughness
-
2
Specific Gravity
2.6-2.7-9999
0
8.4
👆🏻
Transparency
Translucent
Translucent to Opaque
Density
2.6 g/cm3-9999 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.92 kJ/Kg K0.84 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant, Impact Resistant
Heat Resistant
Deposits in Eastern Continents
Asia
Afghanistan, Indonesia, Japan, Russia
China, India
Africa
Kenya
Angola, Egypt, Madagascar, Namibia, Nigeria
Europe
Greece, Hungary, Iceland, Italy, Turkey
Germany, Iceland, Ireland, Italy, Spain, United Kingdom
Others
-
-
Deposits in Western Continents
North America
Canada, Mexico, USA
Canada, USA
South America
Argentina, Chile, Ecuador, Peru
Argentina, Bolivia, Brazil, Colombia, Ecuador
Deposits in Oceania Continent
Australia
New Zealand
Central Australia, Queensland, Western Australia