Rocks and Minerals – Identification of minerals

Introduction:

 The mineral is an inorganic homogeneous natural substance usually crystalline with a definite chemical composition. It is not easy to identify the minerals in the necked eye with a hand specimen of the minerals without proper identification of their structure and chemical composition under a microscope. We can only predict its probability with the help of its properties. In this article, we will discuss the processes of the identification of minerals based on hand specimens.

List of minerals to be identified:

Minerals at a glance:

• Properties:  In short from the above definition we can summarized the main properties of minerals are as follows.
  • Inorganic,
  • Homogeneous,
  • Definite chemical composition & Structure,
  • Natural body without organic particles.
•  Ex. Mica, Tale, Quartz,

Properties of Minerals at a glance in a table:

Basic Identification characteristics	Bauxite	Calcite	Chalcopyrite	Feldspar	Feldspar	Galena	Gypsum	Hematite
1. Colour.	White greyish to ocher yellow	White or colorless	Golden yellow	a) Albite / Plagioclase White/Grey	b)Orthoclase Reddish White / Pink	Lead grey	White / Grey	Reddish-brown (outer surface). Black inner surface
2. Lustre.	Dull & earthy	vitreous to sub-vitreous	Metallic	sub pearly	sub pearly	Metallic	sub-pearly	Metallic
3. Specific gravity	Low	Low	Medium	high to medium	high to medium	Low	low	high
4. Hardness	Variable	3	3.5 – 4.0	> 5	> 5	High (7.4 to 7.6.)	<2.5	5.5 to 6.5
5. Cleavage	Absent	3 sets Perfect: Rhombohedral	Indistinct	2 sets perfect	2 sets perfect	3 sets Perfect:  Cubic	1 set is perfect. 2 other sets are indistinct.	Absent: Parting present
6. Streak	White yellow or pale brown	White	Shining greenish black	White	White	Lead gray	White	Cherry red
7. Special characteristics	Pisolitic and oolitic	Effervesces briskly with cold & dilute HCl	N/A	N/A	N/A	Sometimes marks on paper	crystalline mineral	Slightly Magnetic

Basic identifying characteristics	Magnetite	Mica	Mica	Quartz	Talc	Tourmaline
1. Colour.	Iron Black	a)Muscovite white, silver,	b)Biotite Black	White/Greyish white	White/Whitish Grey / Grey,	commonly black
2. Lustre.	Metallic	pearly luster	pearly luster	vitreous	silky luster	Vitreous, sometimes resinous
3. Specific gravity	very high	very low	very low	Low	low	Medium
4. Hardness	5.5 to 6.5	<2.5	<2.5	> 6 (7)	< 2.5	7-7.5
5. Cleavage	Absent: Parting present	1 set perfect	1 set perfect	Absent	1 set perfect	Indistinct
6. Streak	Black	Uncolored	Uncolored	White	White	White
7. Special characteristics	Strongly Magnetic	transparent and translucent mineral	transparent and translucent mineral	crystalline mineral	soapy feeling	Color range from colorless to brown, red, orange, yellow, green, blue, violet, pink, or hues

5. Picture of Minerals:

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Video

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Conclusion:

These are the identification of minerals, from the above properties of the minerals, we can identify the different minerals at a glance in the field. The process of identification of minerals in hand specimen is very much useful for 1^st time observation. We need more information about the components of particular minerals by laboratory test.

Download Photos of the Minerals