Nephelinite

Porphyry

Nephelinite and Porphyry

Nephelinite

Porphyry

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Definition

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

Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix

History

Origin

Brazil

Egypt

Discoverer

Unknown

Etymology

from French néphéline, from Greek nephelē

From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites

Class

Igneous Rocks

Sub-Class

Durable Rock, Hard Rock

Family

Group

Plutonic

Other Categories

Fine Grained Rock, Opaque Rock

Texture

Aphanitic

Porphyritic

Color

Black, Brown, Green, Grey, White

Black, Brown, Green, Grey, Red, Rust, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Skeletal

Dull

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, Paving Stone

Other Architectural Uses

Curbing

Industry

Construction Industry

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

Construction Aggregate

Medical Industry

Antiquity Uses

Artifacts, Monuments, Sculpture, Small Figurines

Artifacts, Monuments, Sculpture

Other Uses

Commercial Uses

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

Creating Artwork, Gemstone, Jewelry

Types

Peralkaline Nephelinite

Rhomb Porphyry

Features

Host Rock for Lead

Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny

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.

Porphyry is formed in two stages: the magma cools slowly deep within the crust or the magma is cools rapidly as it erupts from a volcano, creating small grains that are usually invisible to naked eye.

Composition

Mineral Content

Clinopyroxene, Nepheline, Plagioclase

Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica

Compound Content

Ca, CaO, Carbon, Cl, MgO

Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Contact Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Biological Weathering, Chemical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Water Erosion, Wind Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Properties

Physical Properties

Hardness

6.56-7

1 7

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Grain Size

Fine Grained

Fracture

Flat

Irregular

Streak

White

Porosity

Less Porous

Luster

Vitreous to Metallic

Dull

Compressive Strength

35.00 N/mm²150.00 N/mm²

0.15 450

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Cleavage

Toughness

2.7

1.7

Specific Gravity

2.4-2.92.5-4

0 8.4

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Transparency

Opaque

Translucent to Opaque

Density

2.5-3 g/cm³2.5-2.52 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.88 kJ/Kg K0.71 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant

Heat Resistant, Impact Resistant

Reserves

Deposits in Eastern Continents

Asia

Japan

China, Kazakhstan, South Korea, Thailand, Turkey, Vietnam

Africa

Rwanda, Tanzania

Egypt, Ethiopia, Ghana, South Africa

Europe

Finland, France, Germany, Great Britain, Hungary, Iceland, Ireland, Italy, Netherlands, Norway, Romania, Sweden, Switzerland

Others

Hawaii Islands

Greenland

Deposits in Western Continents

North America

Canada, USA

Canada, Cuba, Jamaica, USA

South America

Colombia

Bolivia, Brazil, Colombia, Ecuador, Paraguay

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Western Australia

All about Nephelinite and Porphyry Properties

Know all about Nephelinite and Porphyry properties here. All properties of rocks are important as they define the type of rock and its application. Nephelinite and Porphyry belong to Igneous Rocks.Texture of Nephelinite is Aphanitic whereas that of Porphyry is Porphyritic. Nephelinite appears Skeletal and Porphyry appears Dull. The luster of Nephelinite is vitreous to metallic while that of Porphyry is dull. Nephelinite is available in black, brown, green, grey, white colors whereas Porphyry is available in black, brown, green, grey, red, rust, white colors. The commercial uses of Nephelinite are creating artwork, soil conditioner, source of magnesia (mgo) and that of Porphyry are creating artwork, gemstone, jewelry.