Obsidian and Migmatite
Definition
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
Migmatite is typically a granitic rock within a metamorphic host rock which is composed of two intermingled but distinguishable components
History
Origin
Ethiopia
Southern Alps, France
Discoverer
Obsius
Jakob Sederholm
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From the Greek word migma which means a mixture
Class
Igneous Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
Family
Group
Volcanic
Not Applicable
Other Categories
Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Texture
Glassy
Foliated
Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Black, Bluish - Grey, Brown, Brown- Black, Dark Greenish - Grey, Dark Grey to Black
Maintenance
Less
More
Durability
Durable
Durable
Water Resistant
Yes
Yes
Scratch Resistant
Yes
Yes
Stain Resistant
No
No
Wind Resistant
No
No
Acid Resistant
No
No
Appearance
Shiny
Dull, Banded and Foilated
Uses
Architecture
Interior Uses
Decorative Aggregates, Interior Decoration
Countertops, Flooring, Kitchens
Exterior Uses
Garden Decoration
As Building Stone, As Facing Stone
Other Architectural Uses
Not Yet Used
Curbing
Industry
Construction Industry
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
As Dimension Stone, Cement Manufacture, for Road Aggregate, Making natural cement
Medical Industry
Surgery
Not Yet Used
Antiquity Uses
Artifacts, Jewellery
Artifacts
Other Uses
Commercial Uses
Creating Artwork, Mirror, Used in aquariums
Cemetery Markers, Jewelry, Tombstones, Used to manufracture paperweights and bookends
Types
Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Diatexites and Metatexites
Features
Blocks negativity, Helps to protect against depression
Generally rough to touch, Is one of the oldest rock
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
Used
Used
Petroglyphs
Used
Used
Figurines
Not Yet Used
Not Yet Used
Fossils
Absent
Absent
Formation
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.
Migmatites form by high temperature regional and thermal metamorphism of protolith rocks where rocks melt partially due to high temperature.
Composition
Mineral Content
Not Available
Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Aluminium Oxide, NaCl, CaO, Carbon Dioxide, Iron(III) Oxide, FeO, Potassium Oxide, Magnesium Carbonate, MgO, MnO, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Transformation
Metamorphism
Yes
Yes
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional 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, Coastal Erosion, Glacier Erosion
Chemical Erosion, Glacier Erosion, Water Erosion, Wind Erosion
Properties
Physical Properties
Hardness
5-5.5
5.5-6.5
Grain Size
Not Applicable
Medium to Fine Coarse Grained
Fracture
Conchoidal
Irregular
Streak
White
White
Porosity
Very Less Porous
Very Less Porous
Luster
Vitreous
Dull to Pearly to Subvitreous
Compressive Strength
0.15 N/mm2
33
Not Available
Cleavage
Non-Existent
Poor
Toughness
Not Available
1.2
Specific Gravity
2.6-2.7
2.65-2.75
Transparency
Translucent
Opaque
Density
2.6 g/cm3
Not Available
Thermal Properties
Specific Heat Capacity
0.92 kJ/Kg K
10
Not Available
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Pressure Resistant
Reserves
Deposits in Eastern Continents
Asia
Afghanistan, Indonesia, Japan, Russia
China, India, Iran, Iraq, Kazakhstan, Kyrgyzstan, Mongolia, Russia
Africa
Kenya
Cameroon, Ethiopia, Ghana, Kenya, Madagascar, Morocco, Mozambique, Namibia, Nigeria, Tanzania, Togo
Europe
Greece, Hungary, Iceland, Italy, Turkey
Albania, Austria, Bosnia and Herzegovina, Finland, France, Georgia, Germany, Hungary, Italy, Kosovo, Monaco, Norway, Poland, Romania, Serbia, Slovakia, Slovenia, Sweden, Switzerland, Ukraine, United Kingdom
Others
Not Yet Found
Not Yet Found
Deposits in Western Continents
North America
Canada, Mexico, USA
Canada, Costa Rica, Cuba, Mexico, Panama, USA
South America
Argentina, Chile, Ecuador, Peru
Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
New Zealand
New South Wales, New Zealand, Queensland, Victoria
All about Obsidian and Migmatite Properties
Know all about Obsidian and Migmatite properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian belongs to Igneous Rocks while Migmatite belongs to Metamorphic Rocks.Texture of Obsidian is Glassy whereas that of Migmatite is Foliated. Obsidian appears Shiny and Migmatite appears Dull, Banded and Foilated. The luster of Obsidian is vitreous while that of Migmatite is dull to pearly to subvitreous. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Migmatite is available in black, bluish - grey, brown, brown- black, dark greenish - grey, dark grey to black colors. The commercial uses of Obsidian are creating artwork, mirror, used in aquariums and that of Migmatite are cemetery markers, jewelry, tombstones, used to manufracture paperweights and bookends.
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