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
Basanite is a black basaltic rock which mainly contains plagioclase, augite, olivine and nepheline and is formerly used as a touchstone
History
Origin
Ethiopia
-
Discoverer
Obsius
Unknown
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From Latin basanites + -ite
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Family
Group
Volcanic
-
Other Categories
Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Glassy
Aphanitic to Porphyritic
Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Black, Brown, Green, Grey, Red, White
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Shiny
Glassy or Pearly
Architecture
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Homes
Exterior Uses
Garden Decoration
As Building Stone, Garden Decoration, Office Buildings
Other Architectural Uses
-
Whetstones
Industry
Construction Industry
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
Arrowheads, Construction Aggregate, Cutting Tool, Spear Points
Medical Industry
Surgery
-
Antiquity Uses
Artifacts, Jewellery
Artifacts, Monuments
Other Uses
Commercial Uses
Creating Artwork, Mirror, Used in aquariums
As a touchstone, Creating Artwork, Gemstone, In fire-starting tools, Manufacture of tools, Metallurgical Flux, Jewelry, To ignite fire, Used in flintlock firearms
Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Nepheline-Basanite, Analcite-Basanite and Leucite-Basanite
Features
Blocks negativity, Helps to protect against depression
Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate, Used as a touchstone
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.
Basanite is a fine-grained, hard rock that forms when bits of lava shoot out of volcanoes.
Composition
Mineral Content
-
Augite, Feldspar, Ilmenite, Olivine, Plagioclase
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Potassium Oxide, Sodium Oxide, Silicon Dioxide
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Regional Metamorphism
Weathering
✔
✘
✔
✘
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Chemical Weathering, Mechanical 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
5-5.57
1
7
👆🏻
Grain Size
-
Fine Grained
Fracture
Conchoidal
Uneven, Splintery or Conchoidal
Streak
White
White
Porosity
Very Less Porous
Highly Porous
Luster
Vitreous
Waxy and Dull
Compressive Strength
0.15 N/mm2100.00 N/mm2
0.15
450
👆🏻
Cleavage
-
-
Toughness
-
1.5
Specific Gravity
2.6-2.72.5-2.8
0
8.4
👆🏻
Transparency
Translucent
Translucent to Opaque
Density
2.6 g/cm32.7 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.92 kJ/Kg K0.74 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Afghanistan, Indonesia, Japan, Russia
-
Africa
Kenya
Uganda
Europe
Greece, Hungary, Iceland, Italy, Turkey
Germany, Hungary, Italy, Spain
Others
-
Greenland, Mid-Atlantic Ridge
Deposits in Western Continents
North America
Canada, Mexico, USA
USA
South America
Argentina, Chile, Ecuador, Peru
Bolivia, Brazil
Deposits in Oceania Continent
Australia
New Zealand
New South Wales, New Zealand, Queensland, South Australia, Western Australia