Data on rocks and minerals
Appendix A
Appendix A contains a simple description of all the rocks used in the experiment. The
minerals given are those that form the bulk of the rock. The porosity is only given for those
that are porous, all others are not porous.
Basalt
Igneous
Black, fine grained, crystalline rock.
Contains plagioclase feldspar and augite
Cooled quickly on the surface as lava from basic magma.
Vesicular Basalt
Igneous
Black, fine grained, crystalline rock with gas holes.
Contains plagioclase feldspar and augite
Porosity 25%
Cooled quickly on the surface as lava and with gas bubbles getting trapped as the lava
cooled and became viscous.
Dolerite
Igneous
Black or dark grey rock with specks of white. It has a medium grain size and is crystalline.
Contains plagioclase feldspar and augite
Cooled slowly at shallow depths usually as a dyke or sill from basic magma.
Gabbro
Igneous
Coarse grained black and grey speckled rock, crystalline.,
Contains plagioclase feldspar and augite
Cooled very slowly in a large intrusion at depth from basic magma.
Granite
Igneous
Coarse grained rock speckled pink, white and black, crystalline.
Contains quartz, potassium feldspar and plagioclase feldspar
Cooled very slowly at depth in a large intrusion, a plug or batholith from acid magma.
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Microgranite
Igneous
Medium grained rock speckled white and black, crystalline.
Contains quartz. potassium feldspar and plagioclase feldspar
Cooled slowly at depth in a plug from acid magma.
Gneiss
Metamorphic
Coarse grained, black and white banded or streaky rock, crystalline.
Contains quartz, feldspar, hornblende and mica
Crystallised at high temperatures and pressures deep underground under regional
metamorphism of clay or some sandstones. Crystallised without melting.
Schist
Metamorphic
A silvery, coarse grained rock with shiny surfaces which splits into thin layers.
Contains muscovite mica and quartz
Crystallised at medium temperatures and pressures from the regional metamorphism of
clay. Crystallisation took place within solid rock, no melting.
Slate
Metamorphic
A grey, matt, fine grained crystalline rock which splits into thin sheets.
Contains sericite (a mica like mineral) and some quartz.
Crystallised at low temperatures and pressures during regional metamorphism of clay.
Greenish varieties have crystallised from volcanic ash. The clay was metamorphosed
without it melting.
Marble
Metamorphic
A coarsely crystalline rock usually white but may be streaked with yellows, browns or
greens. It will scratch with a metal nail and fizz with acid.
Made of the mineral calcite.
It is formed from the metamorphism, either regional or thermal, of limestone.
Metaquartzite
Metamorphic
A medium grained grey rock which does not scratch with a metal nail or fizz with acid
Made of the mineral quartz
It is formed by the metamorphism, either regional or thermal of pure quartz sandstone
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Metaqreywacke
Metamorphic
This is a greywacke, that is a sandstone with a clay matrix, which has been
metamorphosed.
Made of mostly quartz and chlorite
It has been formed by low grade regional metamorphism
Hornfels
Metamorphic
This is a hard fine grained grey metamorphic rock.
It is made from a variety of minerals including quartz, biotite, andalusite and cordiertite.
It is often produced by thermal metamorphism of clays and shales.
Sandstone
Sedimentary
Sandstone is often crumbly and one can see the individual grains. It can be a wide variety
of colours, white, grey, brown, yellow, green, red and black. It will scratch a metal blade
and usually does not fizz. A drop of water will usually sink into it. It is a fragmental rock.
Made of quartz grains.
Porosity 8% and 12%
It is made by percolating water cementing sand grains together. Sand can accumulate in
a variety of marine and non marine environments.
Breccia
Sedimentary
A rock made from angular fragments more than 1cm long.
The fragments themselves may be igneous, metamorphic or sedimentary but in this
sample they are pieces of quartz set in a sandstone matrix.
Porosity 5%
Percolating fluids have cemented the angular fragments together. Angular fragments
usually accumulate on alluvial fans, scree slopes or the upper reaches of streams.
Limestone
Sedimentary
A white or cream fragmental rock which is easily scratched with a metal nail and fizzes
with acid. A drop of water will usually sink into it.
Made of the mineral calcite. There are two limestones here, one has a higher posity than
the other
Porosity 6% and 10%
It is made from chemically precipitated calcium carbonate which has usually accumulated
in shallow seas.
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Chalk
Sedimentary
Chalk is a bright white very soft powdery rock which fizzes with acid. It is made of the
mineral calcite
Porosity 46%
Chalk is a variety of limestone. It is made from millions of minute shells.
Appendix B Hardness and cleavage of minerals
Mineral
Andalusite
Augite
Biotite
Calcite
Cordierite
Feldspar
potassium
plagioclase
Hornblende
Quartz
Hardness
7
6
3
3
2.7
Cleavage
poor
2 at 90o
1 perfect
3 at 90o
poor
6.5
6.5
6
7
2 at 90o
2 at 90o
2 at 125o
none
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