Sarvajanik College of Engineering and Technology Faculty – Prof. Khushbu Gandhi Prof. Pratima Patel

Name Patel Aashna Parikh Yash Patel Deep Sapan Panchiwala Shivam Parikh Aaysuh Enroll no

A Mineral may be defined as a natural, inorganic, homogeneous, solid substance having a definite chemical composition and regular atomic structure…

Aluminum Bauxite Beryllium Calcite Chromite Clays Copper Fluorite Gold Graphite Gypsm Hematite Iron Magnetite Mica Nickel Quartz Silver Sulfur Uranium etc…

1) Colour 2) Streak 3) Lustre 4) Cleavage 5) Fracture 6) Hardness 7) Form(Habit) 8) Transparency 9) Fluoresence

The colour of a mineral is due to absorption of certain wave lengths of while light by atoms making up the crystal. The remaining wave lengths of white light that are not absorbed, give rise to the colour seen by the observer. Thus dark coloured minerals absorb most of the light whereas red minerals reflect mainly the red light and absorb all others.

CitrinePrasioliteRose Quartz Amethyst Jasper Smokey Quartz Agate Milky Quartz

The colour of the mineral powder is called Streak. It is more reliable than the body colour of the mineral. The streak is obtained by rubbing a mineral against an unglazed porcelain plate, called the streak plate. The study of streak is very useful in case of coloured minerals which often give a much lighter streak than their body colour. For Example: Hematite which appears almost black, gives a red coloured streak…

Streak in different rocks

Lustre is the nature of shining on the surface of the mineral. It is a measure of the reflectivity of light of the mineral surface. There is different types of lustre ….

1) 3) 2) Metallic Shine resembles to surface of metals Ex: galena, pyrite Submetallic A poor metallic lustre Ex: Hematite, chromite, magnetite Vitreous Shine typical of broken, glass, ice,etc… Ex: quartz, felspar

4) Silky Like the shine of silk fibres Ex: Asbestos 5) Resinous Shine is like that of resins Ex: agate, opal 6) Earthy or Dull Shine is almost absent Ex: magnesite, chalk

It is define as the tendency of a crystallized mineral to break along certain definite directions, yielding more or less smooth, plane surfaces. The planes along which the mineral breaks are called the cleavage planes. Cleavage in Mica

Cleavage angle in Amphibole

The fracture of a mineral may be defined as the appearance of the randomly broken surface. In case of fracture, the breaking should be in any other direction than the cleavage. Cleavage appear as Smooth and shining surfaces, but fracture do not produce smooth surfaces. Conchoidal fracture

Hardness is defined as the resistance of a mineral to abrasion or scratching. It is on of the most important diagnostic properties of a mineral. The composition of the mineral appears to have less influence over hardness. For example: Graphite an diamond which possess the same composition but different atomic structures, represent nearly two extremes of hardness in the mineral kingdom, graphite is extremely soft and diamond is extremely hard.

Talk Gypsum Scratched by a finger nail Calcite ApatiteFluorite Scratched by a knife

Quartz Feldspar Scarcely scratched a knife DiamondCorundumTopaz Not Scratched by a knife

This is one of the first observations made when a mineral is examined in a hand specimen. The form represents the common mode of occurrence of a mineral. It is also called habit. there are different types of form like tabular form, elongated form, radiating form, bladed form, fibrous form etc…

Tabular Form Minerals appears as slabs of uniform thickness. Ex: felspar, gypsum Mineral is in the form of thin or thick elongated column like crystals. Ex: beryl, quartz Elongated Form Fibrous Form When the mineral is composed fibers generally easily separable. Ex: Asbestos

Transparency of a mineral may b defined as its capability to pass light through it. Transparent Light passed fully

Semi transparent - Light passed partially Translucent - Only some diffused light is passed through it. Opaque - Light does not pass

Some minerals when exposed in sun light or ultraviolet light, produce a colour quite different form their own. This property of minerals is called Fluorescence. Ex: Green or colourless Fluorite shows a blue or purple colour in ultraviolet light.

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