Porphyry

Rhyolite

Porphyry and Rhyolite

Porphyry

Rhyolite

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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

Rhyolite is a fine-grained igneous rock which is rich in silica

History

Origin

Egypt

North America

Discoverer

Unknown

Ferdinand von Richthofen

Etymology

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

From German Rhyolit, from Greek rhuax lava stream + lithos stone

Class

Igneous Rocks

Sub-Class

Durable Rock, Hard Rock

Family

Group

Plutonic

Volcanic

Other Categories

Fine Grained Rock, Opaque Rock

Coarse Grained Rock, Opaque Rock

Texture

Porphyritic

Aphanitic, Glassy, Porphyritic

Color

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

Grey, White, Light Black

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull

Banded

Uses

Architecture

Interior Uses

Decorative Aggregates, Interior Decoration

Decorative Aggregates, Homes, Hotels, Interior Decoration, Kitchens

Exterior Uses

Garden Decoration, Paving Stone

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

Other Architectural Uses

Curbing

Industry

Construction Industry

Construction Aggregate

Arrowheads, As Dimension Stone, Building houses or walls, Construction Aggregate, Cutting Tool, for Road Aggregate, Knives

Medical Industry

Antiquity Uses

Artifacts, Monuments, Sculpture

Artifacts

Other Uses

Commercial Uses

Creating Artwork, Gemstone, Jewelry

Gemstone, Laboratory bench tops, Jewelry

Types

Rhomb Porphyry

Pumice Rocks, Obsidian Rocks, Perlite Rocks, Porphyritic Rocks.

Features

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

Acidic in nature, Available in lots of colors

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.

Rhyolite is a felsic extrusive rock and due to its high silica content, rhyolite lava is very viscous and is volcanic equivalent of granite.

Composition

Mineral Content

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

Biotite, Feldspar, Hornblade, Plagioclase, Pyroxene, Quartz

Compound Content

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

Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide, Sodium

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

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

Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Chemical Erosion, Sea Erosion, Water Erosion, Wind Erosion

Properties

Physical Properties

Hardness

6-76-7

1 7

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Grain Size

Fine Grained

Large and Coarse Grained

Fracture

Irregular

Sub-conchoidal

Streak

White

Porosity

Less Porous

Highly Porous

Luster

Dull

Earthy

Compressive Strength

150.00 N/mm²140.00 N/mm²

0.15 450

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Cleavage

Toughness

1.7

Specific Gravity

2.5-42.65-2.67

0 8.4

👆🏻

Transparency

Translucent to Opaque

Opaque

Density

2.5-2.52 g/cm³2.4-2.6 g/cm³

0 1400

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Thermal Properties

Specific Heat Capacity

0.71 kJ/Kg K0.71 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant

Heat Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

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

China, India

Africa

Egypt, Ethiopia, Ghana, South Africa

Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa

Europe

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

Germany, Iceland, Ireland, Italy, Spain

Others

Greenland

Deposits in Western Continents

North America

Canada, Cuba, Jamaica, USA

Canada, USA

South America

Bolivia, Brazil, Colombia, Ecuador, Paraguay

Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Western Australia

New Zealand, Queensland, Western Australia

All about Porphyry and Rhyolite Properties

Know all about Porphyry and Rhyolite properties here. All properties of rocks are important as they define the type of rock and its application. Porphyry and Rhyolite belong to Igneous Rocks.Texture of Porphyry is Porphyritic whereas that of Rhyolite is Aphanitic, Glassy, Porphyritic. Porphyry appears Dull and Rhyolite appears Banded. The luster of Porphyry is dull while that of Rhyolite is earthy. Porphyry is available in black, brown, green, grey, red, rust, white colors whereas Rhyolite is available in grey, white, light black colors. The commercial uses of Porphyry are creating artwork, gemstone, jewelry and that of Rhyolite are gemstone, laboratory bench tops, jewelry.