Mineral Property Identify Minerals.pptx

Why Do Different Rocks Have Different Textures?

Rocks are formed in three different ways, leading to different textures:
Igneous Rocks – Form when magma (molten rock) cools and solidifies. Their texture depends on how quickly they cool.
Fast cooling → small crystals (fine-grained texture)
Slow cooling → large crystals (coarse-grained texture)
Sedimentary Rocks – Form from compacted sediments (tiny rock pieces, sand, or minerals). Their texture depends on the size and shape of the particles.
Fine grains (smooth texture) → like clay
Large grains (rough texture) → like sandstone
Metamorphic Rocks – Form when existing rocks undergo heat and pressure. Their texture changes because minerals get rearranged.
Some have layers (foliated texture)
Others are more uniform (non-foliated texture)



Why Do Different Rocks Have Different Textures?

Rocks are formed in three different ways, leading to different textures:
Igneous Rocks – Form when magma (molten rock) cools and solidifies. Their texture depends on how quickly they cool.
Fast cooling → small crystals (fine-grained texture)
Slow cooling → large crystals (coarse-grained texture)
Sedimentary Rocks – Form from compacted sediments (tiny rock pieces, sand, or minerals). Their texture depends on the size and shape of the particles.
Fine grains (smooth texture) → like clay
Large grains (rough texture) → like sandstone
Metamorphic Rocks – Form when existing rocks undergo heat and pressure. Their texture changes because minerals get rearranged.
Some have layers (foliated texture)

Why Do Different Rocks Have Different Textures?

Rocks are formed in three different ways, leading to different textures:
Igneous Rocks – Form when magma (molten rock) cools and solidifies. Their texture depends on how quickly they cool.
Fast cooling → small crystals (fine-grained texture)
Slow cooling → large crystals (coarse-grained texture)
Sedimentary Rocks – Form from compacted sediments (tiny rock pieces, sand, or minerals). Their texture depends on the size and shape of the particles.
Fine grains (smooth texture) → like clay
Large grains (rough texture) → like sandstone
Metamorphic Rocks – Form when existing rocks undergo heat and pressure. Their texture changes because minerals get rearranged.
Some have layers (foliated texture)
Others are more uniform (non-foliated texture)

more uniform (non-foliated texture)



Why Do Different Rocks Have Different Textures?

Rocks are formed in three different ways, leading to different textures:
Igneous Rocks – Form when magma (molten rock) cools and solidifies. Their texture depends on how quickly they cool.
Fast cooling → small crystals (fine-grained texture)
Slow cooling → large crystals (coarse-grained texture)
Sedimentary Rocks – Form from compacted sediments (tiny rock pieces, sand, or minerals). Their texture depends on the size and shape of the particles.
Fine grains


Why Do Different Rocks Have Different Textures?

Rocks are formed in three different ways, leading to diff

1. CLASSIFICATIONS OF ROCKS

2. Rocks are grouped based on: Texture – How the rock looks and feels, determined by the size, shape, and arrangement of its mineral grains. Composition – The types of minerals that make up the rock.

3. What is Texture in Rocks? Texture refers to the size, shape, and arrangement of mineral grains in a rock. It is influenced by how the rock was formed.

4. Why Do Different Rocks Have Different Textures? Rocks are formed in three different ways, leading to different textures: Igneous Rocks – Form when magma (molten rock) cools and solidifies. Their texture depends on how quickly they cool. Fast cooling → small crystals (fine-grained texture) Slow cooling → large crystals (coarse-grained texture) Sedimentary Rocks – Form from compacted sediments (tiny rock pieces, sand, or minerals). Their texture depends on the size and shape of the particles. Fine grains (smooth texture) → like clay Large grains (rough texture) → like sandstone Metamorphic Rocks – Form when existing rocks undergo heat and pressure. Their texture changes because minerals get rearranged. Some have layers (foliated texture) Others are more uniform (non-foliated texture)

5. Because igneous, sedimentary, and metamorphic rocks form differently, their textures are different too!

6. Rocks can also have a distinct grain size: APHANITIC OR PHANERITIC APHANITIC ROCKS – have grains that are too small to see or identify. PHANERITIC ROCKS – have grains, which are big enough to see.

7. ROCK-FORMING MINERALS

8. Learning Objectives Identify common rock-forming minerals using their physical and chemical properties. Identify minerals that are important to society.

9. Minerals are composed of elements such as those found in the periodic table .

10. Characteristics of Minerals: They are naturally-occurring chemical compounds. They are inorganic. They are homogeneous solids. Although not fixed, each mineral has a definite chemical composition which can be described by a chemical formula. Each mineral’s structure arranges atoms in a crystalline pattern.

11. 1.Naturally Occurring Chemical Compounds : This means that minerals are formed through natural processes, without any human involvement. They are found in nature as specific chemical substances made up of elements that are bonded together. For example, the mineral quartz is made up of silicon and oxygen ( SiO ₂), and it forms naturally in the Earth's crust.

12. 2. Inorganic : Minerals are inorganic , meaning they are not derived from living organisms. They don't come from plants or animals. For example, minerals like salt (sodium chloride, NaCl) or gold (Au) are considered inorganic because they do not come from biological processes. This sets minerals apart from things like coal or oil, which come from ancient plants or animals and are considered organic.

13. 3. Solid : Minerals are always solid at room temperature. Their atoms or molecules are tightly packed in a fixed, orderly pattern. 4. Definite Chemical Composition: Each mineral has a specific chemical formula, meaning it contains a consistent ratio of elements. For example, quartz is made of silicon dioxide ( SiO ₂). 5. Crystalline Structure: Minerals have a repeating internal structure, which forms a crystal. This means that the arrangement of atoms follows a regular pattern. The crystal form is a reflection of this structure.

14. Minerals that are made of a single element: GOLD GRAPHITE DIAMOND COPPER

15. Physical Properties of Minerals: Luster Color Streak Hardness Cleavage Fracture Specific gravity

16. Luster Refers to the quality of light on the surface of a rock, crystal, or mineral. A mineral with high luster is very reflective. There are several range of terms used to describe a mineral’s luster – greasy, silky, metallic, earthy, and vitreous

17. Luster Examples

18. Color Caused by the absorption, or lack thereof, of visible light by their crystalline structure. Most minerals have color in various hues, hence, cannot be distinguished by color alone. Quartz, for example, can be colorless white, pink, gray, or purple. Therefore, color should be used conjunction as an aid in mineral identification with other physical properties.

19. Quartz, for example, can be colorless white, pink, gray, or purple. Therefore, color should be used conjunction as an aid in mineral identification with other physical properties.

20. Quartz Purple Amethyst

21. Fluorite Clear Blue Green Purple

22. Streak The color of the powdered mineral produced when it is dragged across an unweathered surface. Streak color is particularly useful in distinguishing metallic minerals such as hematite and galena, that look very similar. Nonmetallic minerals usually have a colorless or white streak.

23. Hardness A mineral’s ability to resist scratching or abrasion. Hardness is determined by comparing the relative hardness of unknown specimen with another mineral with known hardness. Mineral samples are tested for hardness against a set of index minerals scaled from 1 (softest) to 10 (hardest). This is also known as Mohs’ Scale of Hardness.

24. Mohs Scale of Hardness Talc Gypsum Calcite Fluorite Apatite Orthoclase Quartz Topaz Corundum Diamond Hardest Softest

25. Cleavage The tendency of a mineral to split, or cleave, along planes of weakness.

26. Fracture Breaks irregularly, jagged edges

27. Fracture Examples