1.1 Minerals Flashcards
What are minerals?
Substances with a definite chemical composition and atomic structure and formed by the inorganic processes of nature
What are minerals composed of?
Elements
What are the eight most common elements found in minerals?
- oxygen
- aluminium
- calcium
- potassium
- silicon
- iron
- sodium
- magnesium
What is the name of the mineral made from pure silica?
Quartz
What is the symbol for pure silica/quartz?
SiO2
What are the physical properties of minerals that are studied?
- colour
- streak
- lustre
- form or habit
- cleavage
- fracture
- hardness
- relative density
What are the chemical properties of minerals that are studied?
- acid test
* taste test
What does the colour of a mineral depend on?
The colours of the spectrum that it reflects
What does it mean, in terms of reflection of light, if a mineral is colourless?
It allows most light to pass through it
What is the name of a colourless quartz?
Rock crystal
What is the name of a purple quartz?
Amythyst
What is the name of a yellow quartz?
Citrine
What is the name of a brown quartz?
Smoky quartz
What is the name of a pink quartz?
Rose quartz
What is the name of a white quartz?
Milky quartz
What is the streak of a mineral?
The colour of a mineral’s powder
How is the streak of a mineral seen?
By rubbing it on a piece of unglazed porcelain (streak plate)
Is the colour of a mineral’s streak necessarily the same as its normal colour?
No
What colour streak does black haematite have?
Red
What happens if minerals are harder than the streak plate?
They will have no streak
What is the lustre of a mineral?
The amount and quality of light that it reflects
What terms can be used to describe lustre?
- metallic
- vitreous (glassy)
- adamantine
- dull
What is a metallic lustre?
The ordinary lustre of metals
What is a vitreous lustre?
The lustre of broken glass
What is an adamantine lustre?
The brilliant lustre of diamond
What is a dull lustre?
Having little or no lustre
What is the form or habit of a mineral?
The common shape a mineral takes
What terms are used to describe crystal structure?
- crystallised
- crystalline
- cryptocrystalline
- amorphous
What does it mean if a mineral is crystallised?
The mineral occurs as well developed crystals
What does it mean if a mineral is crystalline?
A confused mixture of imperfect crystals
What does it mean if a mineral is cryptocrystalline?
Mere traces of crystalline structure
What does it mean if a mineral is amorphous?
No crystalline structure - this is quite rare
What is the crystal structure of peridot?
Crystallised
What is the crystal structure of fluorite?
Crystalline
What is the crystal structure of gypsum?
Cryptocrystalline
What is the crystal structure of graphite?
Amorphous
What are other common shapes among minerals (not crystalline, crystallised etc.)?
- cubic
- rhombic
- hexagonal
- reniform (kidney shaped)
- nodular
- columnar
- fibrous
- foliated
What does it mean if a mineral is nodular?
Detached, rounded masses
What does it mean if a mineral is foliated?
Thin layers or lamellae
What is the cleavage of a mineral?
The tendency to split along definite planes, known as cleavage planes
What direction are cleavage planes in?
Parallel to crystal forms
How is cleavage described?
Good/poor