Porphyry

Gossan

Porphyry and Gossan

Porphyry

Gossan

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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

Gossan is intensely oxidized, weathered or decomposed rock, usually the upper and exposed part of an ore deposit or mineral vein.

History

Origin

Egypt

Indonesia

Discoverer

Unknown

Cornish Gossen

Etymology

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

From Cornish gossen from gos, blood from Old Cornish guit

Class

Igneous Rocks

Metamorphic Rocks

Sub-Class

Durable Rock, Hard Rock

Durable Rock, Medium Hardness Rock

Family

Group

Plutonic

Other Categories

Fine Grained Rock, Opaque Rock

Fine Grained Rock, Medium Grained Rock, Opaque Rock

Texture

Porphyritic

Rough, Sandy

Color

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

Brown, Brown- Black, Gold, Green, Rust

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull

Dull and Banded

Uses

Architecture

Interior Uses

Decorative Aggregates, Interior Decoration

Countertops, Decorative Aggregates, Interior Decoration

Exterior Uses

Garden Decoration, Paving Stone

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

Other Architectural Uses

Curbing

Industry

Construction Industry

Construction Aggregate

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

Medical Industry

Antiquity Uses

Artifacts, Monuments, Sculpture

Artifacts

Other Uses

Commercial Uses

Creating Artwork, Gemstone, Jewelry

Cemetery Markers, Commemorative Tablets, Gemstone

Types

Rhomb Porphyry

Translocated gossan and Leakage gossan

Features

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

Clasts are smooth to touch, Easily splits into thin plates

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.

Earth movements can cause rocks to be either deeply buried or squeezed and hence the rocks are heated and put under great pressure.

Composition

Mineral Content

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

Apatite, Augite, Biotite, Bronzite, Calcite, Chert, Epidote, Feldspar, Hornblende, Micas, Plagioclase, Pyroxene, Quartz, Sulfides, Zircon

Compound Content

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

Aluminium Oxide, CaO, Fe, FeO, Silicon Dioxide, Sulphur

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

Chemical Erosion, Sea Erosion, Wind Erosion

Properties

Physical Properties

Hardness

6-74-5

1 7

👆🏻

Grain Size

Fine Grained

Fine to Medium Grained

Fracture

Irregular

Conchoidal

Streak

White

White to Grey

Porosity

Less Porous

Highly Porous

Luster

Dull

Metallic

Compressive Strength

150.00 N/mm²-

0.15 450

👆🏻

Cleavage

Toughness

1.7

Specific Gravity

2.5-42.0

0 8.4

👆🏻

Transparency

Translucent to Opaque

Opaque

Density

2.5-2.52 g/cm³-9999 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.71 kJ/Kg K0.24 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant

Heat Resistant, Impact Resistant, Pressure Resistant

Reserves

Deposits in Eastern Continents

Asia

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

China, India, Indonesia, Russia, Singapore, South Korea

Africa

Egypt, Ethiopia, Ghana, South Africa

Cape Verde, Ethiopia, Ghana, South Africa, Western Africa

Europe

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

Albania, France, Germany, Great Britain, United Kingdom

Others

Greenland

Deposits in Western Continents

North America

Canada, Cuba, Jamaica, USA

Canada, USA

South America

Bolivia, Brazil, Colombia, Ecuador, Paraguay

Brazil, Colombia, Ecuador

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Western Australia

New South Wales, South Australia, Western Australia

All about Porphyry and Gossan Properties

Know all about Porphyry and Gossan properties here. All properties of rocks are important as they define the type of rock and its application. Porphyry belongs to Igneous Rocks while Gossan belongs to Metamorphic Rocks.Texture of Porphyry is Porphyritic whereas that of Gossan is Rough, Sandy. Porphyry appears Dull and Gossan appears Dull and Banded. The luster of Porphyry is dull while that of Gossan is metallic. Porphyry is available in black, brown, green, grey, red, rust, white colors whereas Gossan is available in brown, brown- black, gold, green, rust colors. The commercial uses of Porphyry are creating artwork, gemstone, jewelry and that of Gossan are cemetery markers, commemorative tablets, gemstone.