Types of Minerals, Physical Properties of Minerals

1. Mineralogy
Dr. V. R Ghodake
SCOE, Pune.
Unit 1 (a)

2. Mineralogy
It is naturally occurring solid homogeneous substance which has
definite chemical composition and definite atomic structure which
is formed by inorganic processes in nature is called as mineral.
Definition

3. Minerals are divided in to two broad groups
1. Rock forming Minerals
2. Ore forming Minerals
Rock forming
minerals
Ore forming Minerals gives OreOre forming
minerals

4. Rock Forming Minerals- Which are found in abundance in the rock it has
classified in to two groups
1) Primary minerals 2) Secondary minerals
1) Primary minerals: Those which are crystallized directly from magma or lava
known as primary minerals.
Primary minerals are divided in to two groups
a) Essential minerals b) Accessory minerals
i) Essential minerals: Have been used in the definition of the rock Eg. Granite,
Qtz, feldspars
ii) Accessory minerals: Accessory minerals is one whose presence or absence
does not change the definition of rock Eg. Zircon, Sphene, Apatite.

5. In many rocks component minerals grains are either dark or light in color
these are known as essential minerals.
Light colored - Felsic group : the Felsic group includes Qtz. And anhydrous
alumino silicates such as Feldspars and Feldspathoids.
Dark colored - Mafic group : The Mafic group consists of the ferromagnesian
silicates such as Olivine, Pyroxene Amphiboles & dark mica
2) Secondary minerals: It is formed by the alteration of the primary
minerals
Eg. Granite, Qtz. Is primary & Amygdaloidal basalt is secondary

6. Physical Properties of Minerals
Color
It depends upon the absorption and reflection of colored vibration rays by the
minerals.
The color of the minerals is depends upon the amount of light is absorbed and
reflected back by the mineral.

7. Streak
The color of the mineral powder is Streak.
The streak is obtained by rubbing the mineral against streak plate.
Physical Properties of Minerals

8. Luster It is the shining present on freshly broken surface of a mineral.
Luster can be divided in to two types 1) Metallic 2) Non metallic
1) Metallic Luster: Shining like metals Eg. Pyrite, Hematite, Galena.
2) Non metallic Luster: Vitreous, Pearly, Silky, Dull, Glassy, Waxy
Physical Properties of Minerals

9. Hardness
It is defined as the resistance of minerals abrasion or scratching.
It can be tested by finger nail-2, Glass plate-5 & Piece of Quartz-7
Physical Properties of Minerals

10. Cleavage
The tendency of crystallized mineral to break along certain definite directions
yielding more or less smooth, plane surface.
Physical Properties of Minerals

11. Fracture
It is the appearance of broken surface of a mineral. The nature of a broken surface is
called Fracture
Conchoidal Fracture: Broken surface shows curved convex or concave Eg. Quartz
Even: Fracture surfaces are nearly flat or smooth. Eg. Chert
Uneven: Fracture surfaces are rough or irregular
Physical Properties of Minerals

12. FORM- It is the internal atomic arrangement of a
mineral which is manifested outwardly by development of
geometrical shapes or crystal characters.
 CRYSTALLISED: Well defined crystals with perfect cleavage
indicative of perfect atomic arrangement. Eg: Rock crystal
 CRYSTALLINE: Development of small grains &
virtually incipient crystals. Eg: Zebra agate
 AMORPHOUS: Neither crystal nor cleavage. Eg: Talc

13. STRUCTURE / FORM:
Tabular: Eg-Orthoclase.
Elongated/Columnar : Eg-Rock Crystal
Bladed: Eg-Kyanite
Foliated: Eg-Muscovite
Fibrous: Eg-Gypsum
Radiating: Eg-Pyrites
Granular: Eg:-Chromites
Globular: Eg-Hematite
Reniform: Eg-Cavenzite`

14. Sp. Gravity & Chem. Composition
• Specific Gravity: Ratio of Mineral in air to
Water. Eg.: Quartz : 6.25
• Chemical Composition: Definite
Composition of Mineral. Eg. Rock Crystal :
R.SiO4

15. Different Mineral Groups to be
studied during Practical:
• Silicate Mineral Group
• Allumino Silicate Group
• Feldspar Group
• Mica Group
• Zeolite Group
• Ca Ba Bearing Mineral Group
• Ore Mineral Group

16. Olivine

17. Peridotite- Mostly Olivine

18. Pyroxene

19. Gabbro- Pyroxene and Olivine

25. Pink Granite

26. Rock Crystal

27. Andesite- Hornblende
and Biotite and
Plagioclase Feldspar

29. Potassium Feldspar

46. That’s all about
Mineralogy