1. Introduction to Mineralogy Dr
Introduction to Mineralogy Dr. Tark Hamilton Chapter 15: Lecture 33-b Systematic Mineralogy Chemistry of Sulfides
Camosun College GEOS 250

2. Mineral Chemical Classification
Families based on chemical types: Silicate, Sulfide, Element
Groups: Similar structures
e.g rhombohedral carbonates, orthorhombic pyroxenes
Series: Common structure & related cation substitutions
e.g. Augite-Hedenbergite Pyroxenes, Pyrope-Almandite-Spessartite Garnet
Species: A single mineral with 1 structure, definite composition
Calcite, Gold
Varieties: Unusual colours, chemical substitutions, analyses
Chromian (Cr+3) diopside, Ferrian (Fe+3) annite, Manganoan (Mn+2) Calcite, Quartz (var. Adventurine, Amethyst, Citrine etc.)

3. Crystal Structure of Native Elements
Weak Metallic Bonding:
Closest pack array of metal ~cations + Conduction band electrons shared as a uniform crystal field
Few Common Lattice Types:
4 points-FCC-12 cn, HCP, 2 points BCC-8 cn
12-fold coordination: || {111} plane, 3-fold axis

4. Native Sulfur Crystals – Orthorhombic Dipyramidal 2/m 2/m 2/m
fig_15_13

5. Native Sulfur: Orthorhombic 2/m2/m2/m
Stable < 95.5°C
fig_15_03
1.5<H<2, s.g.=2.07, resinous greasy
Dipyramidal Fddd, Z-128, Impurities Se, Te
Colour: yellow-green-orange
Fair Cleavages: (001), (110), (111)
Brittle, sectile, uneven to choncoidal fracture
Occurences: widespread, fumaroles, hotsprings, coals, petroleum deposits, sulfide ores
S 15 mm with Bitumen in Aragonite Cozzo Disi Mine, Sicily, Photo: Rui Nunes 2006

6. Covalent-Network Solids
Diamonds are an example of a covalent-network solid in which atoms are covalently bonded to each other.
They tend to be hard and have high melting points Diamond 3550°C. Stable >105 Atm.
Graphite only melts > 100 Atm, then 4227°C!
Fullerenes from meteorite impacts, soot, low P

7. Native Carbon: Diamond BCC, Graphite Hexagonal, Fullerenes Nets
Diamond: 4/m32/m Hexoctahedral, Z=8 (BCC=4, stuffed), a = Ǻ
V=45.10 Ǻ3, not close packed 34% space used (64% open space) s.g.=3.53, H=10, R.I.=2.435, Octahedrons perfect (111) cleavage densest planes
Greasy-Adamantine Lustre, Strain Birefringence common, Strong colour dispersion, fluid and mineral inclusions common
Geological Occurrence: High Pressure Mantle Rocks: Inclusions of Eclogite, Garnet Peridotite with Cr-Pyrope, Cr-Spinel, Cr-Diopside, Forsterite, Enstatite as inclusions in Kimberlite, Lamproite dykes and pipes, Placers therefrom, residual in sands, microdiamonds from impact sites
Graphite: 2H form: Dihexagonal dipyramidal 6/m2/m2/m, Perfect (0001) basal cleavage, a=2.463 Ǻ, c=6.714 Ǻ, Z=4, Volume = ų
3R form: Trigonal (Hexagonal scalenohedral) 32/m, a=2.456 Ǻ, c= Ǻ, Z=6, Volume = ų, 1<H<2, Iron black-steel grey, greasy, 1<H<2, greasy, micaceous fracture, flexible platelets, 21% of space is filled!
Geological Occurrence: metasediments, veins, pegmatites
Fullerite: Vitreous, amorphous, H=3.5, Basaltic pipe Tajikistan
Other Polymorphs: Chaoite 6/m2/m2/m meteorite black layered with graphite, Lonsdaleite 7<H<8 transparent, impact crater in Russia
fig_15_04
(111) horizontal plane for both

8. Native Carbon: Diamond BCC, Graphite Hexagonal, Fullerenes Nets
Diamond: 3 catat octahedral brown Diamond Ekati Mine, Lac de Gras, NWT, M. Roarke 2006 Mindat.
Graphite: Hexagonal crystal ( cm) Kimmurut, Baffin Island NWT, Rob Lavinsky, Mindat.
Chaoite: Grey mass 15mm in Suevite impact breccia, Ries, Germany, J.F.Carpenter 2007 Mindat.
Other Polymorphs: Lonsdaleite, Fullerite

9. Variation in Natural Diamond Crystals:
a)Octahedron plus Tetrahexahedron (8 equilateral triangle faces + 24 isosceles faces)
b) Hexoctahedron (24 right triangular faces) and
c) spinel law (111) contact twinned tetrahedron (8 triangular + 6 right trapezoidal faces)
fig_15_16

10. How plentiful are diamonds? Can everyone have one?
Availability of Diamonds versus people 2015
surface area of earth
2004 Production
0.3
fraction of continents
35.6
Russia
km2 on continents
31.6
Botswana 28
Kinshasa (Congo)
153.03
km2 kimberlites
20.8
Australia
m2/km2
14.5
South Africa
km2
12.3
Canada
1000
1 km deep mine
142.8
Mcarats/year
1.5303E+11 m3 1
1 macrodiamond/m3
#macrodiamonds
0.2
gram/carat
g/year 2004
world population
years to give everyone a 1 carat diamond
It is also much cheaper to synthesize a diamond than to mine one!

11. Carbon Phase Diagram & Carbon Structures

12. fig_box15_02

13. Sulfides, Sulfosalts & Arsenides
tableun_15_01

14. Metallic Sulfides: Sphalerite (ZnS cubic), Chalcopyrite CuFeS2 (tetragonal) & Tetrahedrite Cu6Cu4(Fe,Zn)2Sb4S13 (Cubic)
fig_15_05

15. Sphalerite Crystal Forms: Octahedron (111) + Dodecahedron (110), 20 faces: 8 incomplete equilateral triangles or hexagons + 12 rectangles
fig_15_21

16. Metallic Sulfides: Sphalerite (ZnS, 43m), Chalcopyrite CuFeS2 (42m) scalenohedral & Tetrahedrite Cu6Cu4(Fe,Zn)2Sb4S13 (43m) hextetrahedral
Sphalerite: 0.7 cm red sphalerite, white dolomite, drusy pyrite, Silurian Lockeport Dolomite, Niagra Falls, ON. (rock from canal dump),M. Wilson photo, Mindat.
Chalcopyrite: & Quartz, Logan Lake Mine, Highland Valley, Kamloops, B.C., 6.5 cm spec J.Nemitz photo, Mindat.
Tetrahedrite: with pyrite & quartz, Brandywine Creek Van Silver Property, B.C., R.O Meyer photo, Mindat.

17. Chalcopyrite Crystal Forms: Distorted Tetrahedron, Disphenoid (2 domes) + Distorted tetragonal prism + dipyramid
fig_15_22

18. Zn & Cd Sulfides: Sphalerite 43m vs Wurtzite: 1-3m & 3-6mm forms
Igneous, Metamorphic, Hydrothermal
fig_15_06

19. Sulfides: CuS Covellite 6/m2/m2/m2/m
fig_15_07
Low temperature supergene copper mineral with a complex structure.
Alternnating sheets of CuS4 tetrahedral with CuS3 hexagonal sheet between.
Intense peacock purple-indigo-blue colours, iridescent, 1.5<H<2,
Perfect basal (0001) cleavage, blades and masses.
Hydrothermal, Fumarolic, epithermal over other copper sulfide deposits.
Cape d’or Basy of Fundy Nova Scotia with Chrysacholla,Stibnite and native Cu. Photo R. Van Dommelen, Mindat.

20. Pyrite Crystal Forms: a) Cube (100) b) Pyritohedron (210), c) Cube +Pyritohedron
d+e) Octahedron + Pyritohedron, f) Penetration twinned Pyritohedron Fe-Cross
fig_15_32

21. Massive Pyrite with Pyritohedrons and Penetration Twinned Cubes
fig_15_34

22. Fe Sulfides: Pyrite & Py after Marcasite
Same mine: 2 generations of mineralization
Pyrite 2/m3 diploidal here striated cubes
High temperature, low acidity polymorph of marcasite. Here primary pyrite crystals in open vein.
Sediments, thermal waters, with Sphalerite
Nanisivik Mine, Baffin Is., Nunavut. Photo J. Betts, Mindat.
Pyrite 2/m3 pseudomorphs after primary marcasite
High temperature, low acidity polymorph of marcasite. Here primary pyrite crystals in open vein.
Sediments, thermal waters, with Sphalerite
Nanisivik Mine, Baffin Is., Nunavut. Photo J. Betts, Mindat.
fig_15_08

23. Marcasite Crystals FeS2 Orthorhombic Tabular on (010) or Prismatic on (001)
fig_15_35

24. Marcasite Crystals FeS2 Spear Twinned and Cock’s Comb Habits
fig_15_36

25. Fe Sulfides: Pyrite, Marcasite, Arsenopyrite
Marcasite 2/m2/m2/m dipyramidal cockscomb, bladed
Low temperature, high acidity polymorph of pyrite
Sediments, thermal waters
Mar + Qtz, Francon Quarry, Montreal. Photo M.Pollinger, Mindat.
fig_15_08
Arsenopyrite 2/m prismatic but common pseudo octahedral crystals with (100) and (001) twin striations. Face centered unit cell
Asp + Qtz, Dufferin Mine, Nova Scotia with Photo R. Van King, Mindat.

26. Arsenopyrite Crystal Forms Monoclinic 2/m (pseudo-orthorhombic) similar to Marcasite but silvery white colour and from Skutterudite by crystal form. Elongate on c or b, Twins: (100) + (001)
fig_15_38