Definition
Variolites are a group of dark green basic igneous rocks which exhibit pale colored spots, or spherules, especially on weathered surfaces, that give them a pockmarked appearance
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
France
Ethiopia
Discoverer
Unknown
Obsius
Etymology
From Latin varius, speckled, variegated
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
Opaque Rock
Opaque Rock
Texture
Glassy, Massive, Porphyritic, Scoriaceous, Vesicular
Glassy
Color
Black, Brown, Light to Dark Grey
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Dull and Soft
Shiny
Architecture
Interior Uses
Floor Tiles, Flooring, Homes, Hotels, Kitchens
Decorative Aggregates, Interior Decoration
Exterior Uses
Garden Decoration, Office Buildings
Garden Decoration
Other Architectural Uses
Curbing
-
Industry
Construction Industry
As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
Medical Industry
-
Surgery
Antiquity Uses
Artifacts, Monuments, Sculpture
Artifacts, Jewellery
Other Uses
Commercial Uses
Cemetery Markers, Creating Artwork
Creating Artwork, Mirror, Used in aquariums
Types
Metamorphic rock
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Features
Has High structural resistance against erosion and climate, Very fine grained rock
Blocks negativity, Helps to protect against depression
Archaeological Significance
Monuments
-
-
Famous Monuments
-
-
Sculpture
-
-
Famous Sculptures
-
-
Pictographs
-
-
Petroglyphs
-
-
Figurines
-
-
Fossils
Absent
Absent
Formation
Variolites are a group of dark green basic igneous rocks that exhibit pale colored spots on weathered surfaces that give them a pockmarked appearance.
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
Olivine, Plagioclase, Pyroxene
-
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Weathering
✔
✘
✔
✘
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
✔
✘
✔
✘
Types of Erosion
-
Chemical Erosion, Coastal Erosion, Glacier Erosion
Physical Properties
Hardness
65-5.5
1
7
👆🏻
Grain Size
-
-
Fracture
Conchoidal
Conchoidal
Streak
White to Grey
White
Porosity
Less Porous
Very Less Porous
Luster
-
Vitreous
Compressive Strength
37.50 N/mm20.15 N/mm2
0.15
450
👆🏻
Cleavage
-
-
Toughness
2.3
-
Specific Gravity
2.8-32.6-2.7
0
8.4
👆🏻
Transparency
Opaque
Translucent
Density
2.9-3.1 g/cm32.6 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.84 kJ/Kg K0.92 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
India, Russia
Afghanistan, Indonesia, Japan, Russia
Africa
South Africa
Kenya
Europe
Iceland
Greece, Hungary, Iceland, Italy, Turkey
Others
-
-
Deposits in Western Continents
North America
Canada, USA
Canada, Mexico, USA
South America
Brazil
Argentina, Chile, Ecuador, Peru
Deposits in Oceania Continent
Australia
-
New Zealand