Porphyry

Obsidian

Porphyry vs Obsidian

Porphyry

Obsidian

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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

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

Egypt

Ethiopia

Discoverer

Unknown

Obsius

Etymology

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

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

Porphyritic

Glassy

Color

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

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

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull

Shiny

Uses

Architecture

Interior Uses

Decorative Aggregates, Interior Decoration

Exterior Uses

Garden Decoration, Paving Stone

Garden Decoration

Other Architectural Uses

Curbing

Industry

Construction Industry

Construction Aggregate

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

Medical Industry

Surgery

Antiquity Uses

Artifacts, Monuments, Sculpture

Artifacts, Jewellery

Other Uses

Commercial Uses

Creating Artwork, Gemstone, Jewelry

Creating Artwork, Mirror, Used in aquariums

Types

Rhomb Porphyry

Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian

Features

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

Blocks negativity, Helps to protect against depression

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.

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

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

Compound Content

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

Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

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

Burial Metamorphism, Cataclastic Metamorphism, Contact 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

Properties

Physical Properties

Hardness

6-75-5.5

1 7

👆🏻

Grain Size

Fine Grained

Fracture

Irregular

Conchoidal

Streak

White

Porosity

Less Porous

Very Less Porous

Luster

Dull

Vitreous

Compressive Strength

150.00 N/mm²0.15 N/mm²

0.15 450

👆🏻

Cleavage

Toughness

1.7

Specific Gravity

2.5-42.6-2.7

0 8.4

👆🏻

Transparency

Translucent to Opaque

Translucent

Density

2.5-2.52 g/cm³2.6 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

Reserves

Deposits in Eastern Continents

Asia

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

Afghanistan, Indonesia, Japan, Russia

Africa

Egypt, Ethiopia, Ghana, South Africa

Kenya

Europe

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

Greece, Hungary, Iceland, Italy, Turkey

Others

Greenland

Deposits in Western Continents

North America

Canada, Cuba, Jamaica, USA

Canada, Mexico, USA

South America

Bolivia, Brazil, Colombia, Ecuador, Paraguay

Argentina, Chile, Ecuador, Peru

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Western Australia

New Zealand

Porphyry vs Obsidian Information

Earth’s outer layer is covered by rocks and these rocks have different physical and chemical properties. As two rocks are not same, it’s fun to compare them. You can also know more about Porphyry and Obsidian Reserves. Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix. 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. These rocks are composed of many distinct minerals. The process of formation of rocks is different for various rocks. Rocks are quarried from many years for various purposes. You can check out Porphyry vs Obsidian information and Porphyry vs Obsidian characteristics in the upcoming sections.

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Porphyry vs Obsidian Characteristics

Though some rocks look identical, they have certain characteristics which distinguish them from others. Characteristics of rocks include texture, appearance, color, fracture, streak, hardness etc. Porphyry vs Obsidian characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Porphyry and Properties of Obsidian. Learn more about Porphyry vs Obsidian in the next section. The interior uses of Porphyry include Decorative aggregates and Interior decoration whereas the interior uses of Obsidian include Decorative aggregates and Interior decoration. Due to some exceptional properties of Porphyry and Obsidian, they have various applications in construction industry. The uses of Porphyry in construction industry include Construction aggregate and that of Obsidian include Arrowheads, Cutting tool, Knives, Scrapers, Spear points.

More about Porphyry and Obsidian

Here you can know more about Porphyry and Obsidian. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Porphyry and Obsidian consists of mineral content and compound content. The mineral content of Porphyry includes Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica and mineral content of Obsidian includes . You can also check out the list of all Igneous Rocks. When we have to compare Porphyry vs Obsidian, the texture, color and appearance plays an important role in determining the type of rock. Porphyry is available in black, brown, green, grey, red, rust, white colors whereas, Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors. Appearance of Porphyry is Dull and that of Obsidian is Shiny. Properties of rock is another aspect for Porphyry vs Obsidian. The hardness of Porphyry is 6-7 and that of Obsidian is 5-5.5. The types of Porphyry are Rhomb Porphyry whereas types of Obsidian are Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Porphyry and Obsidian is white. The specific heat capacity of Porphyry is 0.71 kJ/Kg K and that of Obsidian is 0.92 kJ/Kg K. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Porphyry is heat resistant, impact resistant whereas Obsidian is heat resistant, impact resistant.