The document discusses rock-forming minerals, detailing their composition, formation processes, and classifications. It describes primary minerals, such as ferromagnesians and non-ferromagnesians, and secondary minerals formed from weathering of primary minerals. Additionally, it outlines various mineral classifications based on origin, quantity, specific gravity, and chemical composition.

1. Welcome
PRESENTED BY : SEEMA PRAJAPAT

2. Rock forming minerals:
 Minerals are solid substance and composed of atoms having
an orderly and regular arrangement.
 A Minerals is a naturally- occuring ,homogeneous element or
inirganic compound.
 Most minerals are composed of two or more elements that
combine to form a compound such as gypsum :
CaSO4.2H2O, Olivier, feldspar etc.

3. Formation of minerals:
 When the molten magma solidifies,the different element
present therein freely arrange themselves in accordance with
the attractive forces and geometric form.
 Arrange only 4 oxygen anions(with a radius of 1.32 A°)
around a central silicon action (with a radius of 0.42 A°) ,this
is the arrangement of a tetrahedron.

4. The basic Tetrahedron:

5. Important rock–forming minerals:
 Primary minerals●
- Ferromagnesians
•Olivines Fe, mg
•pyroxenes Ca,Na,Fe,Mg
•Amphiboles,etc. Ca,Na,Fe,My,Al,OH
- Phyllosilicates
•Biotite K,Fe,Mg,So,OH
•Muscovite K,Al, OH.

6. Primary mineral:
 Non – ferromagnesians
•Tectosilicates
~Feldspar,such as:
Anorthite Ca,Al
Albite Na,Al
Orthoclase K,Al
~Quartz _

7. Secondary clay minerals:
 Na,K,Ca,Mg,Fe,Al,OH other then Si and O.
 In the Absence of a crystalline form, the material is
termed as non- crystalline e.g., allophone,chalcedony.

8. Primary minerals:
 The primary minerals are those which are formed owing to the
crystallization of molten magma.
 Orthosilicates
Phyllosilicates
Inosilicates
Tectosilicates _Quartz
_Feldspar.

9. Inosilicates:
 The simplest way to link tetrahedron is to join
one corner with another forming a single chain
structure is PYROXENE.

10. Double chain inosilicate:
 Complex way to link tetrahedron is when two single-chains
are cross –linked to make a double – chain structure,e.g.
AMPHIBOLES

11. Phyllosilicates:
 A complex linkage is in the sheet
structure in which all tetrahedra share
three oxygen ions with the
neighbouring tetrahedra.

12. Inosilicate minerals:
Pyroxene
Amphiboles

13. Phyllosilicates
Mica

14. Phyllosilicates:
 They have sheet structure of tetrahedra where each silicon
ion shares three oxygen ions with adjacent silicon ion to
form a pattern ,like honey –comb.

15. Orthosilicates:
 The orthosilicates are represented by olivine(Fe,Mg)2 SiO4.
 The structure consists of individual silicon –tetrahedra
alternating with positively – charged metal ions which
balance the negative charge of the tetrahedra units.

16. Olivine:

17. Tectosilicates:
 All four oxygen of the silica tetrahedron are shared by the
neighbouring silicon tetrahedra.this means that there are two
ions of oxygen for every ion of silicon thus forming a 3-
dimensional framework.it is represented by the formula SiO2.
 Quartz,feldspar.

18. Quartz:
 The framework of quartz is very
density packed and occurs in a
high degree of purity.
 It is strongly resistant to physical and
chemical weathering as the structure is
densely packed,electrically neutral and
prevents any form of substitution.

19. Feldspar:
 In feldspar,the basic structure is of ring
type,made up of four tetrahedra.
 Depending upon the presence of
diagnostic ions,like K,Na and Ca,that
balance the electric charge,feldspar
are named as orthoclase,albite and
anorthite etc.

20. Some important primary rock forming
minerals:
 FERROMAGNESIAN:
•Olivine Olive – green
•Pyroxene Dark-green
•Amphibole Green- black
•Biotite Black to dark green
 NON- FERROMAGNESIAN:
•Muscovite White,colourless
•Orthoclase Pink (flesh)
•Anorthite White to dark-grey
•Quartz Cloudless to grey.

21. Secondary minerals

22. Secondary minerals:
 The secondary minerals are formed at the earth’s surface by
weathering of the pre-existing primary minerals under
variable conditions of temperature and pressure.
 During weathering water accompanied by CO2 from the
Atmosphere plays an important role in processes, such as
hydrolysis, hydration and solution.

23. Some important secondary minerals:
 Silicates:
●clay minerals - ittlite ,kaolinite,montmorilonite etc.
 Non- silicates:
●oxide,hydroxides of Si,Al and Fe ; Haematite,Geothite;
L Limonite,gibbsite.
●Carbonated: Calcite,dolomite.
●Sulphates : Gypsum
●Phosphate : Apatite,Rock phosphate.

24. Clay minerals:
 The secondary minerals dominantly occurred in the clay
fractions of almost all soils in sedimentary rocks,especially
shales.
 Of the naturally –occurring inorganic crystalline minerals
found in the clay fraction of soils,the most commonly
observed are layer silicates(illite,
montmorilonite,chloride,vermiculite,kaolinite).

25. Classification of minerals:
 Quantity as:
 Essential minerals: Occur in quantities varying from
95-98% e.g.- calcium,silicate minerals.
 Accessory minerals: Occur in subsidiary amount
(2-5%) e.g. Apatite,purity,magnetite.

26. Mode of origin as:
 Primary minerals : formed from crystallization of
magma(molten mass) e.g. Miss,hornblade,quartz.
 Secondary minerals : formed due to decomposition
and/or alternation of primary minerals e.g.
Serpentine,clay minerals.

27. Specific gravity(S.G.) as:
 Light minerals : having S.G. Below 2.85,e.g. Quartz (2.6),
feldspar (2.65), muscovite (2.5 to 2.75).
 Heavy minerals : having S.G. Above 2.85, e.g.
Haematite(5.3), pyrite(5.0), limonite(3.8),augite(pyroxene)
(3.1 to 3.6) ,olivines (3.5).

28. Chemical composition as:
 Native elements- graphite,sulphur,gold,copper.
 Oxides and hydroxide – Quartz,sawriya etc.
 Sulphates- gypsum(CaSO4.2H2O).
 Sulphates- pyrite ( FeS2).
 Carbonate – calcite (CaCO3)
 Halide - rock salt
 Silicates – orthoclase,micas ,olivines etc.

29. Thank you