GEL Mineral ID Professional Project

Transcription

1 Name: Section: Overview: The Department of Earth & Atmospheric Sciences Mineral Laboratory at the Metropolitan State University of Denver offers free non-destructive & certain destructive mineral identification services as part of their geoscientist training program in GEL3050. One or more of these samples will be assigned to you as a student in Mineralogy & Optical Mineralogy. Your responsibility will be to analyze the unknown mineral supervision of the instructing professor according to the clients specification. In the end you will be required to present the client(s) with a full analytical report by the end of the semester. Your work must meet a minimum standard of quality and professionalism. You also will need to return non-destructive tested specimens if requested (Client should have provided SASE or they will pick-up their samples personally from you at the Earth Science laboratories at MSU Denver). For detailed grading see attached Grading Rubric. Professionalism: Since this project requires professional interaction with individuals and businesses in the community, high standards are expected. In order to assure a professional criterion of the outcome, you are assigned a partner. You may work together in collecting data, however, the write-up of the report must be uniquely yours. THIS IS NOT A GROUP PROJECT!!!! The best of the reports will be chosen to be mailed to the client. GRADING: Writing assignments must be turned in by the deadline indicated. Read the WRITING PRIMER in detail BEFORE you submit your paper. Missed deadlines FOR ANY REASON will drop one letter grade as scheduled below with 0% F for work submitted past the final deadline. I will read your paper until I come to the 10 th fault in layout, grammar, spelling, content, concept, format, presentation, expression, design, citation, etc. (Be aware that repeat mistakes will count MORE THAN ONCE!) I will then stop reading / grading, unceremoniously return your work for revision and drop you one full letter grade. Revisions have to be returned by the next deadline and the process is repeated. You will drop one full letter grade every time I reach more than 9 mistakes or if you submit your paper PAST the indicated deadlines. Work submitted past the FINAL SUBMITTAL deadline will ALWAYS receive a 0% F. You have been warned! I WILL PROOFREAD ONE PAGE OF YOUR CHOICE BEFORE SUBMITTAL TO GIVE YOU FEEDBACK. HOWEVER, PROOFREADING OF THE ENTIRE DOCUMENT IS ENTIRELY YOUR JOB. YOUR GRADED SUBMITTAL WILL BE THE INSTRUCTOR S GRADED REVIEW OF YOUR WORK!

2 THIS SHEET IS TO BE RETAINED & ATTACHED TO FRONT OF EVERY SUBMITTAL OF YOUR ASSIGNMENT WARNING!!! NO ASSIGNMENT ACCEPTED WITHOUT THIS SHEET!!! WARNING!!! PROJECT GRADING RUBRIC Name: Course section ID: Overall FINAL Grade: % /250 Your Report must include the following (unless otherwise specified by the client): GStatistically Valid Specific Gravity Analysis (25pts /10%) GChromatography Chemical Analysis w/ graphics (25pts /10%) GXRF w/ labeled graph (25pts /10%) GICP-MS w/ table (25pts/10%) GOptical Analysis (25pts/10%) GXRD w/ labeled graph (25pts/10%) Follow the Project Template! Copy deadline dates and times from calendar here! A 1st SUBMITTAL Comments: Mistakes Points / Percent Q Include THIS cover sheet with your next submittal Deadline to receive A: B 2nd C through F (>0) SUBMITTAL Comments: Mistakes Points / Percent Q Include THIS cover sheet with your next submittal 3 rd & FINAL SUBMITTAL Comments: 79 - number of faults = GRADE PERCENT Calculation of FINAL PROJECT GRADE: Deadline to receive B: Deadline to receive C - F(>0): Assignments received AFTER the last deadline for ANY REASON will be counted as missing and will receive a 0% F! GRADE PERCENT 2.5 = PROJECT POINTS 2.5 =

3 Example write-up of main body of paper: Start with Introduction Cover Letter : Dear [Client], The submitted mineral samples from an abandoned mine just outside of Leadville, CO were subjected to the following non-destructive and destructive analytical procedures as requested. The suite of non-destructive physical tests included observations of color and mineral cleavage as well specific testing for hardness, specific gravity, and streak. Additional analysis consisted of ultraviolet light reaction, both short and longwave, testing for radioactivity and magnetic response, organoleptic (smell, taste) assessment, and effervescence (reaction to dilute acid). Samples were also subjected to nondestructive XRF (x-ray fluorescence) measurement in order to qualify elemental composition. This test is effective for trace elements with an atomic number of Fe (iron) and greater. Estimates for other elements, such as Si, Ca, Mg can also be obtained with this method if the concentrations are sufficiently high. Destructive testing included... Etc.

4 Mineral name: Hemimorphite Mineral group: Sorosilicate Name derivation: Named by Kenngott, because of the mineral's hemimorphic crystal morphology. (Picture) Crystal System: Orthorhombic Crystal Class: Pyramidal Picture of Client Sample Chemical Formula: Zn 4 Si 2 O 7 (OH) 2 H 2 O Chemical Tests: Physical Tests: Solubility test: gelatinizes in acids Hardness: ~5 all directions Researched: Closed tube: yields water (hydrate?). Specimen frosts, decrepitates. Sublimate yellow (hot), white (cold) Open Tube: some water, some white sublimate Microtorch Fusibility: decrepitates, thin edges round = 6 Flame Test: non-indicative, yellow (Na contamination!) Specific Gravity: Researched: g/cm 3 OSingle Pan Hydrostatic: 3.61 g/cm 3 Precision: 98.5% OPycnometer: g/cm 3 Precision: 94.7% GPoint Count Method: N/A Precision: N/A Color: White Color (researched): colorless, white, yellow, green, brown Cleavage: distinct in two directions Cleavage (researched): perfect {110 & 101}, good {001} Thermoluminescence: None observed Streak: white Tenacity: brittle Fluorescence (Short Wave): None Fluorescence (Long Wave): None (researched): SW bluish-green; LW cream-pink Luster: vitreous Luster (researched): vitreous, pearly, subadamantine, rarely silky Phosphorescence: None observed Magnetism: None Radioactivity: None Other (researched): Strongly Pyroelectric Effervescence: None Diaphaneity: Translucent

5 Chromatographic Chemistry: Chromatographic geochemical analysis: Wet Paper Chromatograph(s) R f values: One chromatographic spot with R f 0.93 Researched: 0.94 Definite chemical elements: Zn Possible chemical elements: None Chromatograph interpretation / comments: No chromatographic spot is seen on the raw chromatographic strip. After treatment with 8-hydroxyquinoline spray a yellowish spot develops toward the top of the chromatograph. The same spot fluoresces green under UV light. The calculated R f value, which is the ratio of the spot distance to the chromatographic fluid advancement, is All three observations are a close match to Zn.

6 Instrumental Chemistry: XRF geochemical analysis: XRF geochemical analytical spectrum XRF detected major elements: Zn, Si XRF detected trace elements: Ca, Fe, very minor Mg XRF spectrum interpretation / comments: Zn and Si are definitely present within the sample. The chemical formula should therefore contain those two elements.

7 ICP-MS geochemical analysis: Digestive method and limitations: A small sample split was powdered to 200 mesh and 0.215grams of the powder were subjected to 3mL of concentrated 90 C Aqua Regia for 90 minutes. This digest was filtered and diluted 1:100 in order to be analyzed by the ICP-MS instrument. Aqua Regia leaches are near total for most base metals, partial for Mn, Fe, Sr, Ca, P, La, Cr, Mg, Ba, Ti, B, W and limited for Na, K, Si and Al. The following table lists analytical results in ppm unless indicated as percent (%). 1% = 10,000ppm Si Al Ca Mg K Na Fe Mn Ti Ba P S ppm 13.3% 300 1% Li Be B C V Cr Co Ni Cu Zn Mo Pb ppm % 1,320 Th U Sn Sr Zr As Se Rb Sb Sc Ga Ge ppm 30.5 ppm ppm ICP-MS data interpretation / comments: Y Nb La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Ir Ag Au Pt Zn and Si are the major elements. The lower Si value can be interpreted as partial leaching of silicon from the sample due to the Aqua Regia process.

8 Optical Mineralogy: G Grain Mount Analysis O Thin Section Analysis O Refractometer Test Cleavage: Some parallel to c-axis Color: none Researched: none Pleochroism: none Researched: none Relief: moderate Researched: moderate in epoxy RI: Researched: n á n ß n ã G ISOTROPIC = Isometric Crystal System O ANISOTROPIC Birefringence: ä Researched: ä Extinction: Normal to slightly undulose G UNIAXIAL O BIAXIAL G Positive (+) G Negative (-) O Positive (+) G Negative (-) 2V: 45 Researched: 46 PPL XPL Observation: Some inclusions present. Probably other Zinc minerals, such as Smithonite. Crystals grow in slightly radiating patterns. Crystal System: Orthorhombic Optical Tests interpretation / comments: The optical test results are very indicative of Hemimorphite. The refractory index and resulting birefringence show the greatest deviations. This is most likely due to a more selective crystal orientation during the investigation.

9 XRD Analysis: X-ray Pattern Major Peaks and d-spacing: [Sorted according to your measurement] 2 è d I/I XRD pattern interpretation / comments: ë Rad: CuKá 1 X-ray diffraction unambiguously identifies the unknown mineral as Hemimorphite. The pattern also indicates certain impurities present in the sample such as possible Smithonite (ZnCO 3 ), Goethite (FeO(OH)), and Calcite (CaCO 3 ). Obviously this is an example for ALL tests being performed. Your sheet may be different according to the analysis requested.

10 Mineral name: Hemimorphite Mineral group: Sorosilicate Chemical Formula: Zn 4 Si 2 O 7 (OH) 2 H 2 O (Picture) Locality: Found in an abandoned mine in the Leadville, Colorado area. Sample submitted: John Smith 1234 Side Street Denver, CO jsmith@everything.com phone: To the best of our abilities it was determined that the unknown mineral in question is most likely hemimorphite. Because of the results from our sophisticated XRD analysis coupled with the ICP instrumental chemical assessments and feedback obtained from all other tests, we are confident that your mineral is hemimorphite. Hemimorphite (Zn 4 Si 2 O 7 (OH) 2 H 2 O) is a zinc containing silicate minerals which is often found with other zinc bearing minerals such as sphalerite (ZnS) or Smithonite (ZnCO 3 ). It usually is an altered form of other zinc minerals because of the influence of atmospheric oxygen and water. It occurs close to or within zinc bearing mineral deposits. The mineral will often make beautiful radiating patterns from bladed crystals. It may also occur as botryoidal or bubbly looking green-blue masses. Hemimorphite can be a semi-precious gemstone when transparent. However, this form is rare and typically only small stones of less than 3 carats are found. The most sought after form of hemimorphite is a transparent, gem quality blue to blue-green botryoidal crust that looks like smithonite. However, smithonite will effervesce (fizz) with acid, such as strong vinegar, while hemimorphite will not. Hemimorphite is named after its unusual crystal structure when crystals are visible. Crystals are terminated differently at each end. While one termination is rather blunt, the opposite end is terminated like the point of a pyramid, hence hemimorphite (Hemi = half, morph = shape). Only a few other minerals show hemimorphic character such as tourmaline. The mineral is also strongly pyroelectric, which means it generates electrical charges with changing temperatures. Occurrence: Found in the oxidation zone of zinc-bearing ore deposits. Veins and beds in stratified calcareous rocks common. Usually found with smithsonite, sphalerite, galena, cerussite, anglesite, calcite, aurichalcite, rosasite, hydrozincite, and chrysocolla. References: Perkins, D. ( 2011). Mineralogy, 3 rd ed., Pearson/Prentice Hall Kackstaetter, U.R.( 2011). Mineralogy Optical Mineralogy e-manual, preliminary edition CD, Earthscience Education LLC Tasa, D., Dyar, M.D., and Gunter, M.E. (2008). Mineralogy and Optical Mineralogy. Mineralogical Society of America