Obsidian

Dacite

Obsidian and Dacite

Obsidian

Dacite

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1 Definition

1.1 Definition

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

Dacite is a volcanic igneous rock which is rintermediate in composition between andesite and rhyolite

1.2 History

1.2.1 Origin

Ethiopia

Romania and Moldova, Europe

1.2.2 Discoverer

Obsius

Unknown

1.3 Etymology

From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius

From Dacia, a province of the Roman Empire which lay between the Danube River and Carpathian Mountains where the rock was first described

1.4 Class

Igneous Rocks

1.4.1 Sub-Class

Durable Rock, Medium Hardness Rock

Durable Rock, Soft Rock

1.5 Family

1.5.1 Group

Volcanic

1.6 Other Categories

Opaque Rock

Fine Grained Rock, Medium Grained Rock, Opaque Rock

2 Texture

2.1 Texture

Glassy

Aphanitic to Porphyritic

2.2 Color

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

Bluish - Grey, Brown, Grey, Light to Dark Grey

2.3 Maintenance

Less

2.4 Durability

Durable

2.4.1 Water Resistant

✔ ✘

2.4.2 Scratch Resistant

✔ ✘

2.4.3 Stain Resistant

✔ ✘

2.4.4 Wind Resistant

✔ ✘

2.4.5 Acid Resistant

✔ ✘

2.5 Appearance

Shiny

Vesicular

3 Uses

3.1 Architecture

3.1.1 Interior Uses

Decorative Aggregates, Interior Decoration

Decorative Aggregates, Entryways, Interior Decoration

3.1.2 Exterior Uses

Garden Decoration

As Building Stone, Paving Stone, Garden Decoration

3.1.3 Other Architectural Uses

Not Yet Used

Curbing

3.2 Industry

3.2.1 Construction Industry

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping

3.2.2 Medical Industry

Surgery

Not Yet Used

3.3 Antiquity Uses

Artifacts, Jewellery

Artifacts

3.4 Other Uses

3.4.1 Commercial Uses

Creating Artwork, Mirror, Used in aquariums

Commemorative Tablets, Creating Artwork

4 Types

4.1 Types

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

Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite

4.2 Features

Blocks negativity, Helps to protect against depression

Host Rock for Lead, Is one of the oldest rock

4.3 Archaeological Significance

4.3.1 Monuments

Not Yet Used

4.3.2 Famous Monuments

Not Applicable

4.3.3 Sculpture

Not Yet Used

4.3.4 Famous Sculptures

Not Applicable

4.3.5 Pictographs

Used

4.3.6 Petroglyphs

Used

4.3.7 Figurines

Not Yet Used

4.4 Fossils

Absent

5 Formation

5.1 Formation

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.

Dacitic magma is formed by the subduction of young oceanic crust under a thick felsic continental plate. Further, the Oceanic crust is hydrothermally altered as quartz and sodium are added.

5.2 Composition

5.2.1 Mineral Content

Not Available

Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon

5.2.2 Compound Content

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

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

5.3 Transformation

5.3.1 Metamorphism

✔ ✘

5.3.2 Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Burial Metamorphism, Cataclastic Metamorphism

5.3.3 Weathering

✔ ✘

5.3.4 Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

5.3.5 Erosion

✔ ✘

5.3.6 Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Chemical Erosion

6 Properties

6.1 Physical Properties

6.1.1 Hardness

5-5.52-2.25

1 7

6.1.2 Grain Size

Not Applicable

Medium to Fine Coarse Grained

6.1.3 Fracture

Conchoidal

6.1.4 Streak

White

6.1.5 Porosity

Very Less Porous

Less Porous

6.1.6 Luster

Vitreous

Subvitreous to Dull

6.1.7 Compressive Strength

0.15 N/mm²NA

0.15 450

6.1.8 Cleavage

Non-Existent

Perfect

6.1.9 Toughness

Not Available

6.1.10 Specific Gravity

2.6-2.72.86-2.87

0 8.4

6.1.11 Transparency

Translucent

6.1.12 Density

2.6 g/cm³2.77-2.771 g/cm³

0 1400

6.2 Thermal Properties

6.2.1 Specific Heat Capacity

0.92 kJ/Kg K0.92 kJ/Kg K

0.14 3.2

6.2.2 Resistance

Heat Resistant, Impact Resistant

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

7 Reserves

7.1 Deposits in Eastern Continents

7.1.1 Asia

Afghanistan, Indonesia, Japan, Russia

Not Yet Found

7.1.2 Africa

Kenya

Not Yet Found

7.1.3 Europe

Greece, Hungary, Iceland, Italy, Turkey

France, Greece, Romania, Scotland, Spain

7.1.4 Others

Not Yet Found

7.2 Deposits in Western Continents

7.2.1 North America

Canada, Mexico, USA

USA

7.2.2 South America

Argentina, Chile, Ecuador, Peru

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

7.3 Deposits in Oceania Continent

7.3.1 Australia

New Zealand

New Zealand, South Australia, Western Australia

All about Obsidian and Dacite Properties

Know all about Obsidian and Dacite properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian and Dacite belong to Igneous Rocks.Texture of Obsidian is Glassy whereas that of Dacite is Aphanitic to Porphyritic. Obsidian appears Shiny and Dacite appears Vesicular. The luster of Obsidian is vitreous while that of Dacite is subvitreous to dull. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Dacite is available in bluish - grey, brown, grey, light to dark grey colors. The commercial uses of Obsidian are creating artwork, mirror, used in aquariums and that of Dacite are commemorative tablets, creating artwork.