Porphyry

Skarn

Porphyry and Skarn

Porphyry

Skarn

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Definition

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

Skarns are formed during regional or contact metamorphism and from a variety of metasomatic processes involving fluids of magmatic, metamorphic, and/or marine origin

History

Origin

Egypt

USA, Australia

Discoverer

Unknown

Tornebohm

Etymology

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

From an old Swedish mining term originally used to describe a type of silicate gangue or waste rock.

Class

Igneous Rocks

Metamorphic Rocks

Sub-Class

Durable Rock, Hard Rock

Family

Group

Plutonic

Other Categories

Fine Grained Rock, Opaque Rock

Texture

Porphyritic

Earthy, Mud-rich, Rough

Color

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

Black, Brown, Green, Grey, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull

Uses

Architecture

Interior Uses

Decorative Aggregates, Interior Decoration

Decorative Aggregates, Entryways, Interior Decoration

Exterior Uses

Garden Decoration, Paving Stone

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

Other Architectural Uses

Curbing

Industry

Construction Industry

Construction Aggregate

As a Flux in the Production of Steel and Pig Iron, As a Sintering Agent in Steel Industry to process Iron Ore, As Dimension Stone, Gold and Silver production, Manufacture of Magnesium and Dolomite Refractories

Medical Industry

Antiquity Uses

Artifacts, Monuments, Sculpture

Other Uses

Commercial Uses

Creating Artwork, Gemstone, Jewelry

Creating Artwork, Gemstone, Jewelry, Metallurgical Flux, Source of Magnesia (MgO)

Types

Rhomb Porphyry

Endoskarns

Features

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

Host Rock for Lead, Zinc and Copper Deposits

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Formation

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.

Due to change in environmental conditions, rocks are heated and pressurized deep inside the Earth's surface. Skarn is formed from the extreme heat caused by magma or by the intense collisions and friction of tectonic plates.

Composition

Mineral Content

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

Calcite, Enstatite, Epidote, Garnet, Magnetite, Pyroxene, Titanite

Compound Content

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

Au, CaO, Carbon Dioxide, Cu, Fe, MgO

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

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

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Properties

Physical Properties

Hardness

6-76.5

1 7

👆🏻

Grain Size

Fine Grained

Fracture

Irregular

Streak

White

Light to dark brown

Porosity

Less Porous

Luster

Dull

Waxy and Dull

Compressive Strength

150.00 N/mm²70.00 N/mm²

0.15 450

👆🏻

Cleavage

Slaty

Toughness

1.7

2.4

Specific Gravity

2.5-42.86

0 8.4

👆🏻

Transparency

Translucent to Opaque

Opaque

Density

2.5-2.52 g/cm³2.8-2.9 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.71 kJ/Kg K0.92 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant

Heat Resistant

Reserves

Deposits in Eastern Continents

Asia

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

China, India, Russia, Saudi Arabia, South Korea, Sri Lanka

Africa

Egypt, Ethiopia, Ghana, South Africa

South Africa, Western Africa

Europe

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

United Kingdom

Others

Greenland

Deposits in Western Continents

North America

Canada, Cuba, Jamaica, USA

Canada

South America

Bolivia, Brazil, Colombia, Ecuador, Paraguay

Brazil, Colombia, Paraguay

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Western Australia

Central Australia, Western Australia

All about Porphyry and Skarn Properties

Know all about Porphyry and Skarn properties here. All properties of rocks are important as they define the type of rock and its application. Porphyry belongs to Igneous Rocks while Skarn belongs to Metamorphic Rocks.Texture of Porphyry is Porphyritic whereas that of Skarn is Earthy, Mud-rich, Rough. Porphyry appears Dull and Skarn appears Dull. The luster of Porphyry is dull while that of Skarn is waxy and dull. Porphyry and Skarn are available in black, brown, green, grey, red, rust, white colors. The commercial uses of Porphyry are creating artwork, gemstone, jewelry and that of Skarn are creating artwork, gemstone, jewelry, metallurgical flux, source of magnesia (mgo).