The document discusses various physical properties used to identify minerals, including luster, cleavage, fracture, hardness, specific gravity, and other diagnostic characteristics. It provides definitions and examples of different types of luster (metallic, sub-metallic, non-metallic), cleavage (perfect, imperfect, absent), fracture (even, uneven, hackly, conchoidal), Mohs scale of hardness (ranging from 1 to 10), approaches to measuring specific gravity, and other properties like color, streak, and reaction to acid that can aid identification. The document also includes examples of analyzing physical properties to identify mineral specimens.

2. LUSTRE :
The brilliancy of mineral surface in the reflected light is called as lustre.
It is the general appearance of a mineral surface in reflected light. Lustre of
mineral varies with nature of their surface (smooth or rough) and the quantity of
light reflected. Based on the type of shining, lustres are grouped as Metallic,
Sub-metallic and Non-metallic.
1. Metallic - Shining like polished metals . e.g. Galena, Pyrite, Gold.
2. Sub-metallic – If amount of shining is less, metallic lustre will be described
as Sub-metallic.
3. Non-metallic – Non-metallic lustres are of different types.
i) Vitreous lustre – Shining like broken glass. e.g. Quartz
ii) Pearly lustre - Shining like a pearl e.g. Muscovite, Kyanite
iii) Silky lustre – Shining like silk e.g. Asbestos, Gypsum
iv) Resinous lustre – Shining like resin/wax e.g. Sphalerite, chlorite
v) Greasy lustre – shining like grease e.g. Graphite, Serpentine
vi) Admantine lustre – Shining like Diamond .e.g. Diamond, Zircon
vii) Dull or Earthy – No Shining e.g. Kaolin, Chalk.
Dr. S. V. Kulkarni

3. CLEAVAGE :
The definite direction or plane along which a mineral tend to break easily is
called the cleavage of that mineral. It is the tendency of crystallized mineral to
split or break along certain definite plane. Cleavage plane represents the plane of
weakness in the atomic structure of the mineral. Depending on the ease with
which a crystal breaks and the perfection of the surface obtained , the cleavage is
described as
1. Perfect.
2. Imperfect / Indistinict.
3. Absent.
Depending on the atomic structure, development of cleavage may differ in
different minerals. e.g. Muscovite Mica – One set
Feldspar - Two set
Calcite - Three Sets
Dr. S. V. Kulkarni

4. Dr. S. V. Kulkarni

5. FRACTURE :
Fracture is the nature of randomly broken surface of a mineral. The broken surface
of the mineral other than cleavage direction is called as fracture. On the basis of
nature of broken surface , fractures may be described as
1. Even Fracture – If the broken surface is plain and smooth (almost flat).
2. Uneven Fracture - If the broken surface is rough and irregular.
3. Hackly Fracture - If the broken surface is very rough with sharp projections.
4. Conchoidal Fracture – if the broken surface is smooth and curved. (concave and
convex surface)
Generally the minerals do not show cleavage, break with irregular surface.
Fracture is independent of atomic structure.
Dr. S. V. Kulkarni

6. HARDNESS:
Hardness may be defined as the resistance offered by the mineral to abrasion or
scratching. It is an important physical property used for identification of mineral.
Hardness of a mineral dependent on atomic packing. In the identification of minerals in
hand specimens, only relative hardness is determined . For this, the mineral is compared
with the hardness of a set of ten standard minerals. These reference minerals represent
nearly the complete range of hardness of minerals and are arranged in the increasing order
of hardness. This standard set of ten reference minerals is called Moh’s scale of Hardness.
Moh’s scale of hardness
Name of Mineral Hardness
Talc 1
Gypsum 2
Calcite 3
Fluorite 4
Apatite 5
Feldspar 6
Quartz 7
Topaz 8
Corundum 9
Diamond 10
Dr. S. V. Kulkarni

7. Dr. S. V. Kulkarni

8. SPECIFIC GRAVITY :
Specific gravity of the mineral is the ratio of its weight to an
equal of volume of water. For practical purpose , however, approximation
can be made by holding the mineral specimen in hand and comparing its
weight the following terms are used to describe specific gravity :
1. Heavy - High
2. Medium - Medium
3. Light -Low
OTHER PROPERTIES :
In addition to the above described physical properties of the mineral,
there are some other properties which can be used as diagnostic
character for their identification. These properties are:
1. Test
2. Solubility
3. Smell or odour
4. Magnetism
5. Reaction with acid.
Dr. S. V. Kulkarni

9. Specimen No. :-
A] Chemical composition :- SiO2
B ] Crystal System :- HEXAGONAL
C ] Physical properties :-
1. Form / Habit – Crystalline
2. Colour – Colourless
3. Streak – White / Absent
4. Lustre – Vitreous
5. Cleavage – Absent
6. Fracture – Conchoidal
7. Hardness – Can not be scratched by knife (7)
8. Specific gravity – Medium
D] Diagnostic character – Crystalline form, Absence of cleavage,
Conchoidal Fracture, Hardness 7
On the basis of above physical properties , the mineral may
be identified as QUARTZ
Dr. S. V. Kulkarni

10. Specimen No. :-
A] Chemical composition :- CaCO3
B ] Crystal System :- HEXAGONAL
C ] Physical properties :-
1. Form / Habit – Crystalline / Rhombohedral
2. Colour – White
3. Streak – White
4. Lustre – Vitreous
5. Cleavage – Perfect
6. Fracture – Even
7. Hardness – Can be scratched by knife (3-3.5)
8. Specific gravity – Medium
D] Diagnostic character – Rhombohedral form, Perfect Cleavage
Even Fracture, Hardness 3, Gives +ve
acid test
On the basis of above physical properties , the mineral
may be identified as CALCITE.
Dr. S. V. Kulkarni

11. Specimen No. :-
A] Chemical composition :- KAlSi3O8 (Potassium aluminium
silicate)
B ] Crystal System :- TRICLINIC
C ] Physical properties :-
1. Form / Habit – Crystalline/ Tabular
2. Colour – Flesh red
3. Streak – Absent
4. Lustre – Vitreous
5. Cleavage – Present
6. Fracture – Even
7. Hardness – Can be scratched by knife (6-6.5)
8. Specific gravity – Medium
D] Diagnostic character – Flesh red colour, Perfect cleavage,
Vitreous lustre, Hardness 6, Tabular form
On the basis of above physical properties , the mineral may
be identified as MICROCLINE
Dr. S. V. Kulkarni

12. Specimen No. :-
A] Chemical composition :- KAlSi3O8 (Potassium aluminum
silicate)
B ] Crystal System :- TRICLINIC
C ] Physical properties :-
1. Form / Habit – Massive/ Tabular
2. Colour – White
3. Streak – White
4. Lustre – Vitreous
5. Cleavage – Present
6. Fracture – Uneven
7. Hardness – Can be scratched by knife (6-6.5)
8. Specific gravity – Medium
D] Diagnostic character – White colour, Perfect cleavage,
Vitreous lustre, Hardness 6, Massive form
On the basis of above physical properties , the mineral may
be identified as ORTHOCLASE
Dr. S. V. Kulkarni

13. Specimen No. :-
A] Chemical composition :- KAl2(Al Si3O10) (OH)2 Hydrous Silicate
of K & Al
B ] Crystal System :- MONOCLINIC
C ] Physical properties :-
1. Form / Habit – Flaky / Platy
2. Colour – Colourless/ Transparent
3. Streak – Absent
4. Lustre – Pearly/ Vitreous
5. Cleavage – Perfect
6. Fracture – Even
7. Hardness – Can be scratched by Fingernail (2.7 to 3)
8. Specific gravity – Low
D] Diagnostic character – Colourless, Flaky form, Perfect cleavage,
Pearly lustre,
On the basis of above physical properties , the mineral may be
identified as MUSCOVITE
Dr. S. V. Kulkarni

14. Specimen No. :-
A] Chemical composition :- K(Mg Fe)3 AlSi3O10 (OH)2
B ] Crystal System :- MONOCLINIC
C ] Physical properties :-
1. Form / Habit – Flaky
2. Colour – Deep Brown / Black
3. Streak – Absent
4. Lustre – Pearly/ Vitreous
5. Cleavage – Perfect
6. Fracture – Even
7. Hardness – Can be scratched by Fingernail (2.7 to 3)
8. Specific gravity – Medium
D] Diagnostic character – Brownish Black colour, Perfect cleavage,
Vitreous lustre, Flaky Form
On the basis of above physical properties , the mineral may
be identified as BIOTITE
Dr. S. V. Kulkarni

15. Specimen No. :-
A] Chemical composition :- Al2SiO5
B ] Crystal System :- TRICLINIC
C ] Physical properties :-
1. Form / Habit – Bladed
2. Colour – Brownish red
3. Streak – Absent
4. Lustre – Vitreous to Subvitreous
5. Cleavage – Perfect
6. Fracture – -
7. Hardness – Variable hardness(Lenghtwise 5 – Across 7)
8. Specific gravity – Medium
D] Diagnostic character – Bladed form, Perfect cleavage,
Variable hardness
On the basis of above physical properties , the mineral may be
identified as KYANITE
Dr. S. V. Kulkarni

16. Specimen No. :-
A] Chemical composition :- Ca2Na (Mg,Fe)4 (AlFeTi)(AlSi)8O22(OH)2
Complex Silicate of Ca,Mg,Fe,Al & Na
B ] Crystal System :- MONOCLINIC
C ] Physical properties :-
1. Form / Habit – Crystalline ( Prismatic)
2. Colour – Black / Dark Green
3. Streak – Absent
4. Lustre – Vitreous
5. Cleavage – Present
6. Fracture – Uneven
7. Hardness – Can be scratched by knife (5-5.5)
8. Specific gravity – Medium
D] Diagnostic character – Dark colour, Perfect cleavage,
Vitreous lustre, Hardness 5, Prismatic form
On the basis of above physical properties , the mineral may be
identified as HORNBLENDE
Dr. S. V. Kulkarni

17. Specimen No. :-
A] Chemical composition :- (Ca,Na)(Mg,Fe++,Fe+++,Al)(Si,Al)2O6
B ] Crystal System :- MONOCLINIC
C ] Physical properties :-
1. Form / Habit – Crystalline/ Tabular
2. Colour – Black / Dark Green
3. Streak – Greyish White
4. Lustre – Vitreous
5. Cleavage – Present
6. Fracture – Uneven
7. Hardness – Can be scratched by knife (5-5.5)
8. Specific gravity – Medium
D] Diagnostic character – Dark black colour, Perfect cleavage,
Vitreous lustre, Hardness 5.5, Prismatic
form
On the basis of above physical properties , the mineral may
be identified as AUGITE
Dr. S. V. Kulkarni

18. Specimen No. :-
A] Chemical composition :- Al2O3
B ] Crystal System :- HEXAGONAL
C ] Physical properties :-
1. Form / Habit – Crystalline/ Tabular
2. Colour – Reddish brown
3. Streak – Greyish White
4. Lustre – Admantine
5. Cleavage – Present
6. Fracture – Uneven
7. Hardness – Can not be scratched by knife (9)
8. Specific gravity – High
D] Diagnostic character – Reddish brown colour, Perfect cleavage,
Admantine lustre, Hardness 9,
On the basis of above physical properties , the mineral may
be identified as CORUNDUM
Dr. S. V. Kulkarni

19. Specimen No. :-
A] Chemical composition :- Complex Silicate of Ca, Mg, Fe, Al.
B ] Crystal System :- CUBIC/ISOMETRIC
C ] Physical properties :-
1. Form / Habit – Crystalline/ Dodecahedron
2. Colour – Reddish brown/ Wine Red
3. Streak – Absent
4. Lustre – Resinous
5. Cleavage – Indistinct
6. Fracture – Uneven
7. Hardness – Can not be scratched by knife (6.5-7)
8. Specific gravity – High
D] Diagnostic character – Wine red colour, Crystalline form,
Resinous lustre, Hardness,
On the basis of above physical properties , the mineral may
be identified as GARNET
Dr. S. V. Kulkarni

20. Specimen No. :-
A] Chemical composition :- (Mg,Fe)2 SiO4
B ] Crystal System :- ORTHORHOMBIC
C ] Physical properties :-
1. Form / Habit – Crystalline/ Granular
2. Colour – Olive Green
3. Streak – White
4. Lustre – Vitreous/ Subvitreous
5. Cleavage – Absent
6. Fracture – Uneven
7. Hardness – Can be scratched by knife (6.5)
8. Specific gravity – Medium
D] Diagnostic character – Olive Green colour, Absence of cleavage,
Vitreous lustre, Crystalline form
On the basis of above physical properties , the mineral may
be identified as OLIVINE
Dr. S. V. Kulkarni

21. Specimen No. :-
A] Chemical composition :- Mg3 Si4 O10(OH)2
B ] Crystal System :- ORTHORHOMBIC
C ] Physical properties :-
1. Form / Habit – Foliated /Massive
2. Colour – White/ pale yellow
3. Streak – White
4. Lustre – Pearly
5. Cleavage – present
6. Fracture – Uneven
7. Hardness – Can be scratched by fingernail (1-1.5)
8. Specific gravity – Medium
D] Diagnostic character – Soapy / very soft , Low hardness
Pearly lustre,
On the basis of above physical properties , the mineral may
be identified as TALC
Dr. S. V. Kulkarni

22. Specimen No. :-
A] Chemical composition :- Complex Silicate of Boron and aluminum
B ] Crystal System :- HEXAGONAL
C ] Physical properties :-
1. Form / Habit – Crystalline /Prismatic
2. Colour – Jet Black
3. Streak – Greyish white
4. Lustre – Vitreous
5. Cleavage – Present
6. Fracture – Uneven
7. Hardness – Can not be scratched by fingernail (7-7.5)
8. Specific gravity – Medium
D] Diagnostic character – Jet black colour, Prismatic form
On the basis of above physical properties , the mineral may be
identified as TOURMALINE
Dr. S. V. Kulkarni

23. Specimen No. :-
A] Chemical composition :- Ca SO4.2H2O
B ] Crystal System :- MONOCLINIC
C ] Physical properties :-
1. Form / Habit – Crystalline
2. Colour – White/ Colourless
3. Streak – White
4. Lustre – Vitreous/ Pearly
5. Cleavage – Present
6. Fracture – Uneven
7. Hardness – Can be scratched by fingernail (2-2.5)
8. Specific gravity – Medium
D] Diagnostic character – Crystalline form, Low hardness
On the basis of above physical properties , the mineral may be
identified as GYPSUM
Dr. S. V. Kulkarni

24. Specimen No. :-
A] Chemical composition :- Fe2O3
B ] Crystal System :- HEXAGONAL
C ] Physical properties :-
1. Form / Habit – Massive/ Granular
2. Colour – Reddish brown / Dark brown/ Black
3. Streak – Cherry Red
4. Lustre – Metallic / Submetallic
5. Cleavage – Absent
6. Fracture – Uneven
7. Hardness – Can be scratched by penknife (5-5.5)
8. Specific gravity – Medium to high
D] Diagnostic character – Metallic Lustre, Cherry red streak,
High Sp. gravity
On the basis of above physical properties , the mineral may be
identified as HEMATITE
Dr. S. V. Kulkarni

25. Specimen No. :-
A] Chemical composition :- FeCr2O4
B ] Crystal System :- CUBIC/ ISOMETRIC
C ] Physical properties :-
1. Form / Habit – Crystalline/ Granular
2. Colour – Greyish black/ Dark greenish
3. Streak – Brownish black
4. Lustre – Submetallic / Dull
5. Cleavage – Absent
6. Fracture – Uneven
7. Hardness – Can be scratched by penknife (5-5.5)
8. Specific gravity – High
D] Diagnostic character – Submetallic Lustre, Greyish black Colour,
High Sp. gravity
On the basis of above physical properties , the mineral may be
identified as CHROMITE
Dr. S. V. Kulkarni

26. Specimen No. :-
A] Chemical composition :- MgCO3
B ] Crystal System :- HEXAGONAL
C ] Physical properties :-
1. Form / Habit – Massive
2. Colour – Chalk White
3. Streak – White
4. Lustre – Dull
5. Cleavage – Absent
6. Fracture – Uneven
7. Hardness – Can be scratched by penknife (4)
8. Specific gravity – Medium
D] Diagnostic character – White Colour, Absence of Cleavage
On the basis of above physical properties , the mineral may be
identified as MAGNESITE
Dr. S. V. Kulkarni

27. Specimen No. :-
A] Chemical composition :- Cu Fe S2
B ] Crystal System :- TETRAGONAL
C ] Physical properties :-
1. Form / Habit – Crystalline/ Massive
2. Colour – Brass yellow Colour
3. Streak – Greenish black
4. Lustre – Submetallic
5. Cleavage – Absent
6. Fracture – Uneven
7. Hardness – Can be scratched by penknife (4-4.5)
8. Specific gravity – High
D] Diagnostic character – Brass Yellow Colour, Greenish black
High Sp. gravity
On the basis of above physical properties , the mineral may be
identified as CHALCOPYRITE
Dr. S. V. Kulkarni`

28. Specimen No. :-
A] Chemical composition :- CaCO3.MgCO3
B ] Crystal System :- HEXAGONAL
C ] Physical properties :-
1. Form / Habit – Crystalline/ Massive
2. Colour – White/ Grey
3. Streak – White
4. Lustre – Dull
5. Cleavage – Perfect
6. Fracture – Uneven
7. Hardness – Can be scratched by penknife (3.5-4)
8. Specific gravity – Medium
D] Diagnostic character – Greyish Colour, Reacts with HCl.
Medium Sp. gravity
On the basis of above physical properties , the mineral may be
identified as DOLOMITE
Dr. S. V. Kulkarni

29. Specimen No. :-
A] Chemical composition :- C
B ] Crystal System :- CUBIC/ ISOMETRIC
C ] Physical properties :-
1. Form / Habit – Crystalline/ Granular
2. Colour – Greyish black/Black
3. Streak – Black
4. Lustre – Metallic
5. Cleavage – Perfect
6. Fracture – Uneven
7. Hardness – Can be scratched by penknife (2)
8. Specific gravity – Low to medium
D] Diagnostic character – Metallic Lustre, Greyish black Colour,
Black shining streak
On the basis of above physical properties , the mineral may be
identified as GRAPHITE
Dr. S. V. Kulkarni

30. Specimen No. :-
A] Chemical composition :- (Mg Fe Al)6(Al Si)4 O10 (OH)8
B ] Crystal System :- Monoclinic
C ] Physical properties :-
1. Form / Habit – Folliated
2. Colour – Greenish
3. Streak – Brownish black
4. Lustre – Vitreous
5. Cleavage – Perfect
6. Fracture – Uneven
7. Hardness – Can be scratched by penknife (5-5.5)
8. Specific gravity – High
D] Diagnostic character – Vitreous Lustre, Greyish black Colour,
High Sp. gravity
On the basis of above physical properties , the mineral may be
identified as CHLORITE
Dr. S. V. Kulkarni

31. Specimen No. :-
A] Chemical composition :- CaF2
B ] Crystal System :- CUBIC/ ISOMETRIC
C ] Physical properties :-
1. Form / Habit – Crystalline/ Granular
2. Colour – Yellow/ White
3. Streak – Brownish black
4. Lustre – Vitreous
5. Cleavage – Perfect
6. Fracture – Uneven
7. Hardness – Can be scratched by penknife (4)
8. Specific gravity – Medium to High
D] Diagnostic character – Crystalline form,
High Sp. gravity
On the basis of above physical properties , the mineral may be
identified as FLUORITE
Dr. S. V. Kulkarni

32. Specimen No. :-
A] Chemical composition :- Mg3Si2O5 (OH)4
B ] Crystal System :- MONOCLINIC
C ] Physical properties :-
1. Form / Habit – Fibrous
2. Colour – Greenish
3. Streak – White
4. Lustre – Pearly
5. Cleavage – Perfect
6. Fracture – Uneven
7. Hardness – Can be scratched by penknife (3)
8. Specific gravity – High
D] Diagnostic character – Fibrous form, Pearly lustre
On the basis of above physical properties , the mineral may be
identified as ASBESTOS
Dr. S. V. Kulkarni