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
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
Other Categories
Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Black, Bluish - Grey, Brown, Brown- Black, Dark Greenish - Grey, Dark Grey to Black
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Shiny
Dull, Banded and Foilated
Interior Uses
Decorative Aggregates, Interior Decoration
Countertops, Flooring, Kitchens
Exterior Uses
Garden Decoration
As Building Stone, As Facing Stone
Other Architectural Uses
-
Curbing
Construction Industry
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
As Dimension Stone, Cement Manufacture, for Road Aggregate, Making natural cement
Medical Industry
Surgery
-
Antiquity Uses
Artifacts, Jewellery
Artifacts
Commercial Uses
Creating Artwork, Mirror, Used in aquariums
Cemetery Markers, Jewelry, Tombstones, Used to manufracture paperweights and bookends
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
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.
Mineral Content
-
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
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Chemical Erosion, Glacier Erosion, Water Erosion, Wind Erosion
Grain Size
-
Medium to Fine Coarse Grained
Fracture
Conchoidal
Irregular
Porosity
Very Less Porous
Very Less Porous
Luster
Vitreous
Dull to Pearly to Subvitreous
Specific Gravity
2.6-2.7
2.65-2.75
Transparency
Translucent
Opaque
Density
2.6 g/cm3
-9999 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Pressure Resistant
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
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
Obsidian vs Migmatite Characteristics
Though some rocks look identical, they have certain characteristics which distinguish them from others. Characteristics of rocks include texture, appearance, color, fracture, streak, hardness etc. Obsidian vs Migmatite characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Obsidian and Properties of Migmatite. Learn more about Obsidian vs Migmatite in the next section. The interior uses of Obsidian include Decorative aggregates and Interior decoration whereas the interior uses of Migmatite include Countertops, Flooring and Kitchens. Due to some exceptional properties of Obsidian and Migmatite, they have various applications in construction industry. The uses of Obsidian in construction industry include Arrowheads, Cutting tool, Knives, Scrapers, Spear points and that of Migmatite include As dimension stone, Cement manufacture, For road aggregate, Making natural cement.
More about Obsidian and Migmatite
Here you can know more about Obsidian and Migmatite. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Obsidian and Migmatite consists of mineral content and compound content. The mineral content of Obsidian includes and mineral content of Migmatite includes Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon. You can also check out the list of all Igneous Rocks. When we have to compare Obsidian vs Migmatite, the texture, color and appearance plays an important role in determining the type of rock. 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. Appearance of Obsidian is Shiny and that of Migmatite is Dull, Banded and Foilated. Properties of rock is another aspect for Obsidian vs Migmatite. The hardness of Obsidian is 5-5.5 and that of Migmatite is 5.5-6.5. The types of Obsidian are Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian whereas types of Migmatite are Diatexites and Metatexites. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Obsidian and Migmatite is white. The specific heat capacity of Obsidian is 0.92 kJ/Kg K and that of Migmatite is 0.79 kJ/Kg K. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Obsidian is heat resistant, impact resistant whereas Migmatite is heat resistant, pressure resistant.