Nephelinite

Obsidian

Nephelinite and Obsidian

Nephelinite

Obsidian

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Definition

Nephelinite is a fine-grained or aphanitic igneous rock made up almost entirely of nepheline and clinopyroxene (variety augite).

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

Brazil

Ethiopia

Discoverer

Unknown

Obsius

Etymology

from French néphéline, from Greek nephelē

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

Plutonic

Volcanic

Other Categories

Fine Grained Rock, Opaque Rock

Opaque Rock

Texture

Aphanitic

Glassy

Color

Black, Brown, Green, Grey, White

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

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Skeletal

Shiny

Uses

Architecture

Interior Uses

Decorative Aggregates, Homes, Interior Decoration

Decorative Aggregates, Interior Decoration

Exterior Uses

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

Garden Decoration

Other Architectural Uses

Curbing

Industry

Construction Industry

As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

Medical Industry

Surgery

Antiquity Uses

Artifacts, Monuments, Sculpture, Small Figurines

Artifacts, Jewellery

Other Uses

Commercial Uses

Creating Artwork, Soil Conditioner, Source of Magnesia (MgO)

Creating Artwork, Mirror, Used in aquariums

Types

Peralkaline Nephelinite

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

Nephelinite 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

Clinopyroxene, Nepheline, Plagioclase

Compound Content

Ca, CaO, Carbon, Cl, 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

Contact Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Water Erosion, Wind Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Properties

Physical Properties

Hardness

6.55-5.5

1 7

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Grain Size

Fine Grained

Fracture

Flat

Conchoidal

Streak

White

Porosity

Less Porous

Very Less Porous

Luster

Vitreous to Metallic

Vitreous

Compressive Strength

35.00 N/mm²0.15 N/mm²

0.15 450

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Cleavage

Toughness

2.7

Specific Gravity

2.4-2.92.6-2.7

0 8.4

👆🏻

Transparency

Opaque

Translucent

Density

2.5-3 g/cm³2.6 g/cm³

0 1400

👆🏻

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

Japan

Afghanistan, Indonesia, Japan, Russia

Africa

Rwanda, Tanzania

Kenya

Europe

Greece, Hungary, Iceland, Italy, Turkey

Others

Hawaii Islands

Deposits in Western Continents

North America

Canada, USA

Canada, Mexico, USA

South America

Colombia

Argentina, Chile, Ecuador, Peru

Deposits in Oceania Continent

Australia

New Zealand

All about Nephelinite and Obsidian Properties

Know all about Nephelinite and Obsidian properties here. All properties of rocks are important as they define the type of rock and its application. Nephelinite and Obsidian belong to Igneous Rocks.Texture of Nephelinite is Aphanitic whereas that of Obsidian is Glassy. Nephelinite appears Skeletal and Obsidian appears Shiny. The luster of Nephelinite is vitreous to metallic while that of Obsidian is vitreous. Nephelinite is available in black, brown, green, grey, white colors whereas Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors. The commercial uses of Nephelinite are creating artwork, soil conditioner, source of magnesia (mgo) and that of Obsidian are creating artwork, mirror, used in aquariums.