non silicates - oxides Flashcards
which oxides are most likely to come up in the exam? (so you should probably know)
- magnetite
- illmentite
- heamatite
- Chromite
- spinel
- geothite
- manganite
- cuprite
identify the following mineral: habit: - subhedral and individual grains usually difficult to see lustre: - metallic hardness: -5/6 clevage: - none additional properties: - weak magnetism Colour: Silver Streak: pale silver
illmenite
what are the diagnositc properties of illmentie?
- no clevage
- weak magnetism
- pale grey streak
identify the following mineral: habit: - anhedral colour: - red to reddish brown streak colour: - red hardness: - 5/6 lustre: - earthy/dull Cleavage: - none other proeprties: - weak magnetism
heamaite
what are the diagnostic properties of heamatite?
RED STREAK COLOUR and weak magnetism
identify the following mineral: habit: - bladed subhedral colour: - green/dark grey but lighter than other oxides streak: - dark brown/black lustre: - metallic clevage: -none Hardness: - 5/6
chromite
identify the following mineral: habit: -anhedral massive colour: - black but could have red/brown due to oxidation of iron streak: - dark grey/black lustre: -greasy/earthy hardness: -5/6 clevage: -none other properties: - strong magnetism
magnetite
what us THE diagnostic property of magnetite?
its strong magnetism
what are the identifiable properties of spinel?
black with lighter speckles/spots
which hydroxide can be identified by its botryoidal aggregation?
geothite
identify the following mineral: habit: - acicular aggregation: -radial colour: dark grey weak magnetism
manganite
corundum is anothe oxide that i couldnt find a specimne of. what does it look like?
its got black square crystals (so cubic habit) and is in a bigger white rock. it will be VERY HARD
how would you identify cuprite?
it has a very strong metal smell.
red to black colour
very reflective in cavities
Identify the following lab specime: Habit: - equant/isometric Aggregation: - Botryoidal (specific specimine) Colour: Dark grey (almost like a pencil) Streak colour: - distinctive pale yellow streak Hardness: - 7/8 (scratches the quartz glass) Lustre: - silky Cleavage: - none visible with the Botryoidal aggregation
Goethite
An oxide leaves a very pale streak colour, what is it?
Goethite
What does the corundum lab sample look like?
It is literally a white rock with some small black square shaped crystals in it (these being the corundum
Identify the following oxide: Habit: - square shaped/cubic Aggregation: -granular Colour: A purplish/brown/black is colour Streak: - no streak HardnesS: - 9/10 (scratches the quartz glass) Lustre: - greasy
Corundum - the hardness should be the identifier
Some of the oxide samples have a very generalised/ similar appearance. What is this?
They are dark with fine grained crystals that almost sparkle within the rock matrix
Identify the follwing mineral: Habit: - non visible due to massive aggregation Lustre: - metallic greasy lustre Hardness: - 3/4 Colour: - dark grey Additional proeprties: - very weak magnetism No cleavage visible, doesn’t mean its not there
Chromite
Identify the following oxide: Habit: - massive to individual grains not visible Aggregation: -massive Colour: - pale red colour Streak colour: - brown/red streak colour Hardness: - 3/4 Scratched by steel nail Lustre: - earthy/dull
BAUXITE - this is a hydroxide
Magnetite and bauxite both leave a distinct red/brown streak colour. How would you distinguish between the two?
Their actual colour. Heamatite id dark wheras bauxite is a red rock
Illmenite are VERY similar to one another. How can you tell them apart?
Illmenite looks a lot more “greasy” than chromite, whereas chromite looks more like a black rock with induvidual shiny grains in it
What properties would allow you to identify spinel?
- dark grey colour
- leaves dark brown streak
- hardness 3/4 (scratched by the quartz glass)
Has very weak lustre
What is one of the diagnostic properties of spinel?
It leaves a dark brown streak
How do you distinguish between Illmenite and chromite?
The lustre- Illmenite has a metallic lustre whereas chromite does not
