PETROLOGY (GROUP 5)

It deals with the various aspects of rocks such as origin occurrence, mineral and chemical composition, texture, structure, and physical properties of rocks

petrology

A naturally occurring solid mass or aggregate of minerals. It is categorized by the minerals included, its chemical composition and the way it is formed.

rocks

Study of rocks in thin section by means of a petrologic microscope. It deals with the descriptive part of rocks.

petrography

A scientist who studies petrography, examines mineral makeup and textural features of rocks to understand their origin and history.

ferdinand zirkel

give the 2 ways on how petrographers examine rocks

macroscopic examination and microscopic examination

This involves observing the rock with the naked eye or with the aid of a hand lens.

macroscopic examination

This involves using a microscope, particularly a petrographic microscope, to examine thin sections of the rock.

microscopic examination

• Observed rocks using the naked eye

• Help identify color, texture, size, and mineral

macroscopic examination (1)

• Uses petrographic microscope to analyze thin section of rock

• Helps understand the formation and history of rocks

microscopic examination (1)

The types and proportions of minerals that make up the rocks.

mineralogy

The size, shape and arrangement of minerals in the rock

texture

• Course Grained - Large and easy to see.

• Fine Grained - Small.

texture (grain size)

Also known as Petrogenesis It deals with origin and Formation of Rocks, especially Igneous Rocks.

petrogeny

These are formed from the cooling and solidification of molten rock, either magma (below the Earth's surface) or lava (above the surface).

igneous rocks

• Forms when magma cools and solidifies beneath the earth’s surface.

• Have larger crystals due to slower cooling.

• Called as Plutonic Rocks

• Examples are: Granite, Diorite, Gabbro

intrusive

• Form from lava

• Have smaller crystals resulting from rapid cooling.

• Also called as Volcanic Rocks

• Examples are: Basalt, Rhyolite, Andesite

extrusive

Found in continents

granite

Found in ocean

basalt

Found in volcanic arc

dacite

Found in continents

rhyolite

These are formed from the accumulation and cementation of sediments, which can be fragments of other rocks, organic material, or minerals that precipitate from water.

sedimentary rocks

• Form from accumulation and mechanical weathering of debris.

• Examples are: Sandstone, Shale, Conglomerate

clastic

• Form when mineral constituents in solution become supersaturated and inorganic precipitation occurs.

• Examples are: Rock salt, Gypsum, Limestone

chemical

• Result from the accumulation of plants or animal debris.

• Examples are: Coal, Limestone, Oil Shale

organic

These are formed when existing rocks (igneous or sedimentary) are changed by heat, pressure, or chemical reactions

metamorphic rocks

• Have layer or bonded appearance produced by exposure to heat and directed pressure.

• Examples are: Slate, Schist- mica, Gneiss

foliated

• Do not have layered or bonded appearance.

• They often lack minerals that form plates.

• Examples are: Marble, Quartzite, Hornfels

non-foliated