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
Dacite is a volcanic igneous rock which is rintermediate in composition between andesite and rhyolite
Origin
Ethiopia
Romania and Moldova, Europe
Discoverer
Obsius
Unknown
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From Dacia, a province of the Roman Empire which lay between the Danube River and Carpathian Mountains where the rock was first described
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Soft Rock
Other Categories
Opaque Rock
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Glassy
Aphanitic to Porphyritic
Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Bluish - Grey, Brown, Grey, Light to Dark Grey
Durability
Durable
Durable
Appearance
Shiny
Vesicular
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Entryways, Interior Decoration
Exterior Uses
Garden Decoration
As Building Stone, Paving Stone, Garden Decoration
Other Architectural Uses
-
Curbing
Construction Industry
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping
Medical Industry
Surgery
-
Antiquity Uses
Artifacts, Jewellery
Artifacts
Commercial Uses
Creating Artwork, Mirror, Used in aquariums
Commemorative Tablets, Creating Artwork
Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite
Features
Blocks negativity, Helps to protect against depression
Host Rock for Lead, 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.
Dacitic magma is formed by the subduction of young oceanic crust under a thick felsic continental plate. Further, the Oceanic crust is hydrothermally altered as quartz and sodium are added.
Mineral Content
-
Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Burial Metamorphism, Cataclastic 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
Grain Size
-
Medium to Fine Coarse Grained
Fracture
Conchoidal
Conchoidal
Porosity
Very Less Porous
Less Porous
Luster
Vitreous
Subvitreous to Dull
Specific Gravity
2.6-2.7
2.86-2.87
Transparency
Translucent
Translucent
Density
2.6 g/cm3
2.77-2.771 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Afghanistan, Indonesia, Japan, Russia
-
Europe
Greece, Hungary, Iceland, Italy, Turkey
France, Greece, Romania, Scotland, Spain
Deposits in Western Continents
North America
Canada, Mexico, USA
USA
South America
Argentina, Chile, Ecuador, Peru
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
New Zealand
New Zealand, South Australia, Western Australia
Obsidian vs Dacite 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 Dacite characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Obsidian and Properties of Dacite. Learn more about Obsidian vs Dacite in the next section. The interior uses of Obsidian include Decorative aggregates and Interior decoration whereas the interior uses of Dacite include Decorative aggregates, Entryways and Interior decoration. Due to some exceptional properties of Obsidian and Dacite, 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 Dacite include As dimension stone, Construction aggregate, For road aggregate, Landscaping.
More about Obsidian and Dacite
Here you can know more about Obsidian and Dacite. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Obsidian and Dacite consists of mineral content and compound content. The mineral content of Obsidian includes and mineral content of Dacite includes Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon. You can also check out the list of all Igneous Rocks. When we have to compare Obsidian vs Dacite, 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, Dacite is available in bluish - grey, brown, grey, light to dark grey colors. Appearance of Obsidian is Shiny and that of Dacite is Vesicular. Properties of rock is another aspect for Obsidian vs Dacite. The hardness of Obsidian is 5-5.5 and that of Dacite is 2-2.25. The types of Obsidian are Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian whereas types of Dacite are Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Obsidian and Dacite is white. The specific heat capacity of Obsidian is 0.92 kJ/Kg K and that of Dacite is 0.92 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 Dacite is heat resistant, impact resistant, pressure resistant, wear resistant.