Mineral Deposit Geology and Models Flashcards
_____ which occurs at the surface can be worked by cheap open pit methods.
Large, low-grade deposits
_____ will necessitate more expensive underground methods of extraction
Thin tabular vein deposits
_____, aided by the savings from bulk handling of large daily tonnages, has led to a trend towards the large scale mining of low grade orebodies
Open pitting
Ore bodies of _____ can be mined more cheaply than those of _____, particularly when they include barren zones
regular shape, irregular shape
For an open pit mine, the shape and attitude of an orebody will also determine ____
how much waste has to be removed during mining
if an orebody viewed in plan is longer in one direction than the other, we can designate this long dimension as its _____.
strike
The inclination of the orebody perpendicular to the strike.
dip
The longest dimension of the orebody.
axis
The _____ of the axis is measured in the vertical
plane ABC
plunge
Can be measured in any other plane, the usual choice being the plane containing the strike,
pitch or rake
if the orebody is fault-controlled then the _____ may be measured in the fault plane.
pitch
These bodies are extensive in two dimensions but have restricted development in their third dimension.
Tabular orebodies
Frequently pinch and swell out as they are followed up or down a stratigraphical sequence
Vein
Sometimes called fissure-veins
Veins
Can create difficulties during both exploration and mining often because only the swells are workable.
pitch-and-swell structure
Tabular orebodies that are vertical or sub-vertical
pipes or chimneys
Horizontal or subhorizontal tabular orebodies
mantos
Ore minerals are peppered throughout the body of the host rock in the same way as accessory minerals are disseminated through igneous rock; in fact, they often are accessory minerals.
Disseminated orebodies
Closed-spaced veinlets cutting the host rock forming an interlacing network
stockwork
Mineralization of this type generally fades _____ into sub-economic mineralization and the boundaries of the orebody are assay limits.
gradually outwards
(Skarn or contact metamorphic or pyrometasomatic or replacement deposit) Mineralogy
calc-silicate minerals
- diopside
- wollastonite
- andradite garnet
- actinolite
(Skarn or contact metamorphic or pyrometasomatic or replacement deposit) Ore Mineralogy
- iron
- copper
- tungsten
- graphite
- zinc
- lead
- molybdenum
- tin
- uranium
- talc
these orebodies show a considerable development in two dimensions, parallel to the bedding and perpendicular to it, referred to as stratiform.
Sedimentary host rocks
Any type or types of orebody, concordant or discordant, which are restricted to a particular part of the stratigraphical column
Strata-bound
Parallel to the bedding and perpendicular to it,
Stratiform
Sedimentary host rocks e.g
- Limestone hosted
- Argillaceous hosted
- Arenaceous hosted
- Rudaceous hosted (Placer Deposit)
Sedimentary iron and manganese formations and evaporites occur scattered through the stratigraphical column where they form very extensive beds conformable with the stratigraphy.
Chemical sediments
Volcanic hosts
Volcanogenic Massive sulfides
VMS are generally stratiform bodies, _____ or _____, developed at the interfaces between volcanic units or at sedimentary interfaces.
lenticular, sheet-like
Plutonic hosts
Layered Mafic Intrusions (LMI)
Plutonic hosts (Magmatic Segregation Deposits)
- Layered Mafic Intrusions (LMI)
- Layered Cr-Pt MAfic-Ultramafic Complexes
-Cu-Ni-Pt Segregation - Anorthosite - Titanium
- Ultramafic volcanic rock associations - Cu - Ni
Known also as “Mesothermal Au”, “Slate belt-type Au”, “Archean Au”, “deposits related to solution-
remobilization”
Orogenic Gold
Restricted to the ultramafic rocks of the various ophiolite belts where climatic conditions and physiographic favor laterization processes.
Laterite
high iron content, low nickel, cobalt, magnesia, and silica.
Limonite
high nickel, cobalt, and magnesia, but low iron content.
Garnierite/Saprolite
is an aluminium ore. It is the world’s main source of aluminium. It consists mostly of the minerals gibbsite Al(OH)3, boehmite γ-AlO(OH) and diaspore α-AlO(OH), mixed with the two iron oxides goethite and hematite, the clay mineral kaolinite and small amounts of anatase TiO2.
Bauxite
Bauxite source rocks
Nepheline Syenite
Clay
Clayey limestone
Clay shales
Crystalline gneisses
Basalt
Alluvium
