Picrite

Obsidian

Picrite and Obsidian

Picrite

Obsidian

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Definition

Picrite is a variety of high-magnesium olivine basalt that is very rich in the mineral olivine

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

Hawaii Islands

Ethiopia

Discoverer

Unknown

Obsius

Etymology

From Greek pikros bitter + -ite, 19th century

From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius

Class

Igneous Rocks

Sub-Class

Durable Rock, Hard Rock

Durable Rock, Medium Hardness Rock

Family

Group

Volcanic

Other Categories

Fine Grained Rock, Opaque Rock

Opaque Rock

Texture

Earthy, Rough

Glassy

Color

Black, Brown, Green, Grey, Pink, White, Yellow

Black, Blue, Brown, Green, Orange, Red, Tan, Yellow

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Rough and Shiny

Shiny

Uses

Architecture

Interior Uses

Countertops, Decorative Aggregates, Homes, Interior Decoration

Decorative Aggregates, Interior Decoration

Exterior Uses

As Building Stone, As Facing Stone, Garden Decoration, Paving Stone

Garden Decoration

Other Architectural Uses

Curbing

Industry

Construction Industry

As a Sintering Agent in Steel Industry to process Iron Ore, Cement Manufacture, for Road Aggregate, Manufacture of Magnesium and Dolomite Refractories, Roadstone, Used for flooring, stair treads, borders and window sills.

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

Medical Industry

Surgery

Antiquity Uses

Artifacts, Monuments, Sculpture

Artifacts, Jewellery

Other Uses

Commercial Uses

As a Feed Additive for Livestock, As armour rock for sea walls, Metallurgical Flux, Pottery, Source of Magnesia (MgO)

Creating Artwork, Mirror, Used in aquariums

Types

Oceanite

Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian

Features

Host Rock for Lead

Blocks negativity, Helps to protect against depression

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Formation

Picrite is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.

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

Biotite, Olivine, Plagioclase, Pyrrhotite

Compound Content

Al, CaO, Carbon Dioxide, Mg, MgO

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, Impact Metamorphism, Regional Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Properties

Physical Properties

Hardness

6.85-5.5

1 7

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Grain Size

Fine Grained

Fracture

Uneven

Conchoidal

Streak

White, Greenish White or Grey

White

Porosity

Less Porous

Very Less Porous

Luster

Subvitreous to Dull

Vitreous

Compressive Strength

189.00 N/mm²0.15 N/mm²

0.15 450

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Cleavage

Toughness

2.1

Specific Gravity

2.75-2.922.6-2.7

0 8.4

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Transparency

Opaque

Translucent

Density

1.5-2.5 g/cm³2.6 g/cm³

0 1400

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Thermal Properties

Specific Heat Capacity

0.88 kJ/Kg K0.92 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant

Heat Resistant, Impact Resistant

Reserves

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

All about Picrite and Obsidian Properties

Know all about Picrite and Obsidian properties here. All properties of rocks are important as they define the type of rock and its application. Picrite and Obsidian belong to Igneous Rocks.Texture of Picrite is Earthy, Rough whereas that of Obsidian is Glassy. Picrite appears Rough and Shiny and Obsidian appears Shiny. The luster of Picrite is subvitreous to dull while that of Obsidian is vitreous. Picrite is available in black, brown, green, grey, pink, white, yellow colors whereas Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors. The commercial uses of Picrite are as a feed additive for livestock, as armour rock for sea walls, metallurgical flux, pottery, source of magnesia (mgo) and that of Obsidian are creating artwork, mirror, used in aquariums.