Please enable JavaScript.
Coggle requires JavaScript to display documents.
Diamonds - Coggle Diagram
Diamonds
uses/properties/intro
uses
industrial - drill tips
cutting and grinding
jewellery
types
uncut - natural - only this used for resource estimates
cut faces to make them shine
synthetic
may affect demand
pure C high p and T
structure
carbon in octahedral structure
hardest natural mineral
properties
mid density higher than quartz - channel depositable
good thermal conductor, good electrical insulator - too expensive for these uses
mining
viability based on grade and value of individual stones
canada low value high grade
lesotho high value low grade
where are kimberlite pipes?
craton areas
old rocks
subduction zones
sources of C
oceanic limestone subduction releases C into magma
can move through time
same way hawaii does but no pipes hawaii
canada
hot spot feeds pipes, hot spot moves, chain of pipes
mining
extremely steep
pipe localised and mine narrow
open-pit blasting
shafts and adits
alluvial/marine - onshore/offshore dredging
exploration
indicator mineral sampling
specific assemblage of minerals to indicate whether there are kimberlite pipes nearby
geophysics
contrast pipe and country rock (denisty)
drilling and pipe models
recreate surface geology using subsurface drilling
can't mine deeper than 1km
cross-cutting boreholes
geological environments
cratons and correct tectonic settings
kimberlite pipes
rocks formed at high temp/pressure
cooled inside intrusions deep in crust
K and Mg ultramafic
olivine and garnet and mantle xenoliths
weakness in crust transports hot basaltic magma intrusion
reaches close to or at surface
localised crater
kimberlite rocks to surface
diamond presence
pressure and C
deep enough for high P
C not equally distributed so not all mantle rich enough
placer deposit
erosion of kimberlite pipes
accumulation due to density and abrasion resistance
accumulate in basement rock pockets - potholes
gravels enriched in diamonds in channel basin
deserts with flashfloods
offshore deposits
entrainment sorting picks light material away and leaves behind dense diamond material
suspension sorting - denser deposited first
processing