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
Quartzite is a non-foliated metamorphic rock that forms by the metamorphism of pure quartz Sandstone
History
Origin
Ethiopia
-
Discoverer
Obsius
Unknown
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From quartz + -ite
Class
Igneous Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Family
Group
Volcanic
-
Other Categories
Opaque Rock
Medium Grained Rock, Opaque Rock
Texture
Glassy
Foliated, Granular
Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Black, Blue, Brown, Green, Light Grey, Purple, White, Yellow
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Shiny
Lustrous
Architecture
Interior Uses
Decorative Aggregates, Interior Decoration
Countertops, Decorative Aggregates, Flooring, Homes
Exterior Uses
Garden Decoration
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Other Architectural Uses
-
Curbing
Industry
Construction Industry
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
Arrowheads, As Dimension Stone, Cement Manufacture, Construction Aggregate, Cutting Tool, for Road Aggregate, Making natural cement, Production of Glass and Ceramics, Rail Track Ballast, Roadstone
Medical Industry
Surgery
-
Antiquity Uses
Artifacts, Jewellery
Artifacts, Jewellery, Monuments, Sculpture
Other Uses
Commercial Uses
Creating Artwork, Mirror, Used in aquariums
An Oil and Gas Reservoir, As armour rock for sea walls, Cemetery Markers, Commemorative Tablets, In aquifers, Laboratory bench tops, Petroleum reservoirs, Soil Conditioner, Source of Magnesia (MgO), Tombstones, Used in aquariums
Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Orthoquartzite and Metaquartzite
Features
Blocks negativity, Helps to protect against depression
Generally rough to touch, Is one of the oldest rock
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.
Quartzite forms from sandstone and the mineral quartz being put under extreme heat and pressure.
Composition
Mineral Content
-
Chlorite, Epidote, Hematite, Kyanite, Magnetite, Muscovite or Illite, Quartz
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, MgO, Sodium Oxide, Silicon Dioxide
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Hydrothermal Metamorphism, Regional 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
Chemical Erosion, Coastal Erosion, Water Erosion, Wind Erosion
Physical Properties
Hardness
5-5.56-7
1
7
👆🏻
Grain Size
-
Medium Grained
Fracture
Conchoidal
Uneven, Splintery or Conchoidal
Streak
White
White
Porosity
Very Less Porous
Less Porous
Luster
Vitreous
Vitreous
Compressive Strength
0.15 N/mm2115.00 N/mm2
0.15
450
👆🏻
Cleavage
-
Indiscernible
Toughness
-
1.9
Specific Gravity
2.6-2.72.6-2.8
0
8.4
👆🏻
Transparency
Translucent
Transparent to Translucent
Density
2.6 g/cm32.32-2.42 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.92 kJ/Kg K0.75 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
China, India, Israel, Russia, South Korea, Thailand, Turkey
Africa
Kenya
Ethiopia, Morocco, South Africa, Zimbabwe
Europe
Greece, Hungary, Iceland, Italy, Turkey
England, Italy, Norway, Scotland, Sweden, United Kingdom
Others
-
Greenland
Deposits in Western Continents
North America
Canada, Mexico, USA
Bahamas, Canada, USA
South America
Argentina, Chile, Ecuador, Peru
Brazil, Colombia, Venezuela
Deposits in Oceania Continent
Australia
New Zealand
New Zealand, Queensland, Western Australia