UNIVERSITY OF SOUTH ALABAMAMississippi Valley -type ore deposits •Named after the type mines in Missouri, Tennessee and other sites in the Mississippi Valley •Low temperature (epithermal)

GY 302: Crystallography & Mineralogy

Lecture 14: Carbonates, Nitrates, Borates

Instructor: Dr. Douglas Haywick

UNIVERSITY OF SOUTH ALABAMA

Mineral Quizzes results

1: Chromite (39%) 2: Hematite (92%) 3. Gibbsite (100%) 4: Diaspore (92%) 5: Limonite (85%) 6: Zincite (92%) 7: Ilmenite (12%)

Bonus: Sphalerite (69%)

2015: Average: 73.1%

Highest grade: 101% (2)

2014 Average: 81.5%

Highest grade: 103%

You Guys: Average: 87.2%

Highest grade: 98% (3)

Last Time (before the break)

Halides Select minerals

Occurrences and Associations

Featured minerals: Evaporites

Halite (NaCl) Crystal: Isometric Pt. Group: 4/m 3 2/m Habit: cubic, hopper crystals SG: 2.17; H: 2.5 L: vitreous; Str: white Col: white (various shades) Clev: perfect [100], [010], [001] Optics: Isotropic (n=1.544)

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Name derivation: From the Greek halos (salt)

Halide Minerals

Fluorite (CaF2) Crystal: Isometric Pt. Group: 4/m 3 2/m Habit: cubic, octahedral crystals SG: 3.0-3.25; H: 4 L: vitreous; Str: white Col: variable Clev: [111] perfect Optics: Isotropic (n=1.434)

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Name derivation: From its elemental composition containing fluorine

Halide Minerals

http://www.electric-lady-land.com/004.%20Fluorite-LW.jpg

Evaporite Formation

First Last Aragonite (ooids) Dolomite Gypsum Anhydrite Halite Sylvite*

Today’s Agenda

Carbonates, Nitrates, Borates 1. Select carbonate minerals

2. Sphalerite and galena (left over sulfides)

Featured mineral association: MVT-ores

(Mississippi Valley-type ores)

Carbonates, Nitrates, Borates


•There are 70 carbonate minerals, over 60 borates and a few nitrates



•All 3 types of minerals involve planar anion groups….

•… with the exception of BO44- which is tetrahedral



•All 3 types of minerals involve planar anion groups….

•… with the exception of BO44- which is tetrahedral

•Oxygen atoms are strongly covalently bonded in the anion (especially in CO3

2-), but bonding between the anion and the cation is ionic


•Carbonates are by far the most important of the Class V minerals, three of which (calcite, dolomite and aragonite) comprise about 40% of all sedimentary rocks and more than 20% of the entire geological column.

•They are both biogenic and chemically precipitated

Carbonates

Calcite Group (3 2/m): Calcite (CaCO3) Magnesite (MgCO3) Siderite (FeCO3) Rhodochrosite (MnCO3) Smithsonite (ZnCO3)

Carbonates

Calcite Group (3 2/m): Calcite (CaCO3) Magnesite (MgCO3) Siderite (FeCO3) Rhodochrosite (MnCO3) Smithsonite (ZnCO3) Dolomite Group (3): Dolomite (CaMg(CO3)2) Ankerite (CaFe(CO3)2) Kutnahurite (CaMn(CO3)2) Zincian Dolomite (CaZn(CO3)2)

Carbonates

Calcite Group (3 2/m): Calcite (CaCO3) Magnesite (MgCO3) Siderite (FeCO3) Rhodochrosite (MnCO3) Smithsonite (ZnCO3) Dolomite Group (3): Dolomite (CaMg(CO3)2) Ankerite (CaFe(CO3)2) Kutnahurite (CaMn(CO3)2) Zincian Dolomite (CaZn(CO3)2)

Calcite and Dolomite both possess 6-fold (Octahedral) coordination

The only difference is that dolomite lacks 2/m symmetry because of alternating Ca-Mg layers

Carbonates

Calcite Group (3 2/m): Calcite (CaCO3) Magnesite (MgCO3) Siderite (FeCO3) Rhodochrosite (MnCO3) Smithsonite (ZnCO3) Aragonite Group (2/m 2/m 2/m): Aragonite (CaCO3) Witherite (BaCO3) Strontianite (SrCO3) Cerussite (PbCO3)

Calcite (CaCO3) Crystal: Trigonal Pt. Group: 3 2/m Habit: euhedral (rhombs); scalenohedral (“dog tooth”), bladed, stalactitic, massive SG: 2.71; H: 3 L: vitreous, waxy; Str: white Col: white (various shades) Clev: {101} Perfect Optics: uniaxial - ne= 1.486; nw= 1.658

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Name derivation: From the Latin, calx, meaning lime

Carbonate Minerals

Calcite (CaCO3) Occurrence: widespread sedimentary and epithermal breccia (MVT) deposits; biogenic mineral (trilobites, echinoderms etc.) Associated Mins: sedimentary: dolomite, aragonite, quartz; MVT: dolomite, sphalerite, galena, fluorite May be confused with: most rhombohedral carbonates (possibly distinguished because of its reactivity with HCl) Uses: many

Carbonate Minerals

Calcite is used for: 1) Polarizing filters in optics (Iceland spar)

2) a flux in steel manufacturing

3) building materials, floor tiles, marble vanities

4) Portland cement

Carbonate Minerals




4) Portland cement

Carbonate Minerals

CaCO3 CaO heat <10% Mg 0% Pyrite




4) Portland cement

Carbonate Minerals

CaCO3 CaO + clay “clinker” burned




4) Portland cement

Carbonate Minerals

CaCO3 CaO + clay “clinker”

“concrete”

Dolomite (CaMg(CO3)2) Crystal: Trigonal Pt. Group: 3 Habit: euhedral rhombohedral, saddles SG: 2.86; H: 3.5 L: vitreous; Str: white Col: white to grey, pink Clev: {101} Perfect Optics: uniaxial - ne= 1.500; nw= 1.680

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Name derivation: French mineralogist Deodat Guy Tancrede Gratet de Dolomieu (1750-1801)

Carbonate Minerals

Dolomite (CaMg(CO3)2) Occurrence: widespread sedimentary and epithermal breccia (MVT) deposits, replacement mineral, synsedimentary sabkha deposits (pseudo-dolomite) Associated Mins: sedimentary: calcite, gypsum, anhydrite, aragonite; MVT: calcite, sphalerite, galena, fluorite May be confused with: most rhombohedral carbonates Uses: agriculture

Carbonate Minerals

The Dolomite Problem

Carbonate Minerals

Discussion http://www.cse.anl.gov/nuclear_enviro_processes/interfacial_processes/dolomite_problem.html

(A) Schematic side view of the dolomite (104) surface. (B) Lateral-force microscopy image of a dolomite surface with pristine and reacted regions, imaged during reaction. The reaction effectively stops when the surface is coated by the reaction product. (C) Real-time X-ray reflectivity data of dolomite in saturated and supersaturated solutions, showing the reaction kinetics, the self-limiting reaction and the irreversibility with respect to the pristine surface, R(t)/R(0) = 1.

Aragonite (CaCO3) Crystal: Orthorhombic (pseudo hexagonal) Pt. Group: 2/m 2/m 2/m Habit: euhedral, hexagonal prisms SG: 2.94; H: 3.5-4 L: vitreous; Str: white Col: colourless (pinkish) Clev: poor{010}, {110} Optics: Biaxial - nα= 1.530; nβ= 1.682; nγ= 1.686

Name derivation: From its type location, Aragon in Spain

Carbonate Minerals

Aragonite (CaCO3) Occurrence: blueschist metamorphic facies; common biogenic mineral (corals, bivalves, etc.) Associated Mins: metamorphic assemblage: glaucophane, pumpellyite May be confused with: calcite Uses: none

Carbonate Minerals

Calcite-Aragonite stability field

http://www.geol.lsu.edu/henry/Geology3041/lectures/26MetaReactions/Fig26-1.jpg

Rhodochrosite (MnCO3) Crystal: Hexagonal (Trigonal) Pt. Group: 3 2/m Habit: botryoidal, banded, euhedral (rhombs); massive SG: 3.69; H: 4 L: vitreous, waxy; Str: white Col: pink, pinkish red, yellow Clev: {101} Perfect Optics: uniaxial - ne= 1.596; nw= 1.816

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Name derivation: From the Greek rhodon for rose and chroma for color.

Carbonate Minerals

Rhodochrosite (MnCO3) Occurrence: epi- to mesothermal ore deposits in igneous host rocks; high temperature metamorphic rocks Associated Mins: copper sulfides, galena, sphalerite, barite May be confused with: rhodonite (H=6) Uses: secondary ore of Mn

Carbonate Minerals

Smithsonite (ZnCO3) Crystal: Hexagonal (Trigonal) Pt. Group: 3 2/m Habit: botryoidal SG: 4.5; H: 4.5 L: vitreous, waxy; Str: white Col: blue, grey, grayish white Clev: {101} Perfect Optics: uniaxial - ne= 1.625; nw= 1.850

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Name derivation: After James Smithson (1765-1829), English mineralogist who financed the Smithsonian!

Carbonate Minerals

Smithsonite (ZnCO3) Occurrence: secondary ore mineral in oxidized zinc deposits (supergene?) Associated Mins: hemimorphite, cerrusite, anglesite, pyromorphite May be confused with: hemimorphite Uses: secondary ore of Zn

Carbonate Minerals


Borax (Na2B4O7·10H2O) Crystal: Monoclinic Pt. Group: 2/m Habit: massive, prismatic (rare) SG: 1.71; H: 2 to 2.5 L: earthy, vitreous; Str: white Col: blue, grey, grayish white Clev: [100], [110] Perfect Optics: Biaxial - nα= 1.447; nβ= 1.469; nγ= 1.472

Name derivation: From the Arabic buraq, for white.

Borate Minerals

Borax (Na2B4O7·10H2O) Occurrence: evaporite mineral (playas) Associated Mins: Kernite, Colemanite (other borates) May be confused with: lots, but it is soluble Uses: source of boron, chemicals

Borate Minerals

Nitratine (NaNO3) Crystal: Trigonal Pt. Group: 3 2/m Habit: massive, granular SG: 2.26; H: 1.5-2 L: vitreous; Str: white Col: white, brown, yellow Clev: {101} Perfect Optics: uniaxial - ne= 1.580; nw= 1.330

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Name derivation: duh…

Nitrate Minerals

Nitratine (NaNO3) Occurrence: extremely arid playa lakes in Chile Associated Mins: gypsum, halite, niter, iodate minerals May be confused with: N/A Uses: fertilizer

Nitrate Minerals

MVT-ores

Mississippi Valley-type ore deposits •Named after the type mines in Missouri, Tennessee and other sites in the Mississippi Valley

•Low temperature (epithermal) sedimentary ore deposits

•Primary minerals produced: dolomite (saddle), calcite, fluorite and some old friends….

MVT-ores

Some of the most spectacular mineral specimens come from MVT mines. Euhedral crystals indicate significant pore space was present during mineralization

MVT-ores

Galena (PbS) Sphalerite (ZnS)

MVT-ores

MVT-ores are common around the world

MVT-ores

Saddle dolomite

Sphalerite

Original country rock (dolostone)

Country rock is almost always brecciated

MVT-ores

Chalk Board

Today’s Stuff To Do 1. Poster preparation discussion (1 hr)

2. Carbonates and Halides in lab

Online

1. Test

Thursday

1. Sulfates and Phosphates (Lecture 15)

GY 302: Crystallography and Mineralogy

Lecture 14: Carbonates etc.

Instructor: Dr. Doug Haywick [email protected]

This is a free open access lecture, but not for commercial purposes.

For personal use only.

Documents

UNIVERSITY OF SOUTH ALABAMAMississippi Valley -type ore deposits •Named after the type mines in Missouri, Tennessee and other sites in the Mississippi Valley •Low temperature (epithermal)