1 / 29

CL in Support of Interpreting Gem Deposits

CL in Support of Interpreting Gem Deposits. G. E. Harlow 1 E. Sahm 1,2 J. Hunt 1,3. 1 American Museum of Natural History, New York, NY 2 University of Utah, Salt Lake City, UT 3 California Institute of Technology, Pasadena, CA. MVE02-3-1 (SSS). Instrumentation.

finn
Download Presentation

CL in Support of Interpreting Gem Deposits

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CL in Support of Interpreting Gem Deposits G. E. Harlow1 E. Sahm1,2 J. Hunt1,3 1 American Museum of Natural History, New York, NY 2 University of Utah, Salt Lake City, UT 3California Institute of Technology, Pasadena, CA MVE02-3-1 (SSS)

  2. Instrumentation • Hitachi S-4700 Field-Emission SEM with BSE, EDS and a Gatan MonoCL3 detector & monochromator system (Peltier-cooled high-sensitivity PMT). The grating is a low-dispersion (21.6nm / mm slit width), with peak response (blaze wavelength) at 500nm and useful range of ~200 - 1200 nm.

  3. CL Applications • Cathodoluminescence is an extremely powerful technique for examining zoning in minerals and can lead to fundamental interpretations about how they formed. • Targets in this presentation: • Jadeitites: jadeite, zircon, grossular? • Corundum deposits: ruby, sapphire, painite

  4. Guatemalan Jadeitites • Jadeitites have been interpreted as crystallizations from aqueous fluids derived from subductions channels based, in large part, on CL observations. • In Guatemala there are two distinct serpentinite mélanges containing jadeitite, North and South of the Motagua fault. • How do the CL signatures of the minerals compare between the two distinct sources.

  5. Phengite Qtz Jd-2 Zrn Omph Jd-1 Ttn SOUTH MVE02-8-6 Phengite Jadeitite, San Jose

  6. Panchromatic Jadeite-phengite rock (MVE02-8-6 – SOUTH) Jadeite 480 nm Blue 270 nm UV Jd-2 Jd-1 SOUTH

  7. Zircon, Secondary Electrons Jd-2 Zrn Jd-1 BSE Zircon Panchromatic Jadeite-phengite rock(MVE02-8-6 –SOUTH) Zircon 500 315 240 410 Panchromatic

  8. 315 nm UV 410 nm Blue 505 nm Green 685 nm Red

  9. Zircon in lawsonite-eclogite(MVE02-6-1 – SOUTH) Zircon, Panchromatic 490 230 230 nm UV 490 nm Blue-green

  10. Pmp Grs Jd BSE Pmp-Grs-Jadeitite(MVE04-20-1 – SOUTH) Jadeite 330 600 940 Panchromatic CL

  11. MVE04-20-1 Pmp-Grs-Jadeitite Jadeite SOUTH BSE Panchromatic CL Panchromatic CL

  12. MVE04-20-1 Pmp-Grs-Jadeitite Jadeite 300 nm UV Panchromatic 600 nm Green 940 nm IR

  13. Pmp Grs Jd BSE Panchromatic Pmp-Grs-Jadeitite(MVE04-20-1 – SOUTH) Grossular 590 335 ~850 475 Panchromatic

  14. NORTH Jadeitite, Río La Palmilla, North of MFZ(MVJ84-9D) 2 cm across (courtesy of S. Sorensen)

  15. NORTH

  16. Panchromatic CL image of same area. Note healed fracture in jadeite grain. NORTH

  17. Close-up from previous image NORTH

  18. Altered Jadeite (MVJ84-9B)at boundary between Jd and Ab+Ne NORTH

  19. Room Temperature Spectrum Imaging Scale bar is 1 about micrometer. Spectrum Image (40 X 40 pixels) of adjacent area NORTH

  20. Point 0 Point 1 Nepheline? Albite? Darker Jadeite Lighter Jadeite ~700 ~560 ~700 ~560 ~480 Point 2 Point 3 Room temperature CCD CL spectracourtesy of Paul Mainwaring

  21. Zircon, Meta(?)-Jadeitite(MVJ84-9C – NORTH) 547 279 350 279 nm UV 350 nm UV 547 nm Green

  22. Jadeite-Phengite rock (MVE02-8-6 -- SOUTH) • Comparison of CL Spectra from Jadeite • UV to IR peaks, but too soon to make generalizations other than color zoning observed by Sorensen and co-workers. 480 270 Pmp-Grs-Jadeitite(MVE04-20-1 -- SOUTH) Altered Jadeite(MVJ84-9B -- NORTH) Jadeite 330 ~700 ~560 ~480 600 940

  23. Zircon in lawsonite-eclogite (MVE02-6-1 -- South) • Comparison of CL spectra from zircon • Main peak near 500nm and lowest near 250nm, but … • All are features show only primary growth. 490 230 Jadeite-phengite rock(MVE02-8-6 -- South) Zircon, Meta(?)-Jadeitite(MVJ84-9C -- North) Zircon 547 500 315 240 279 350 410

  24. BSE Ruby (107643), Mogok, Burma inMarble w/ Spinel, Blue Cancrinite, Sodalite, Scapolite, Phlogopite, etc. 694nm - Cr 320 840 Panchromatic

  25. 320 nm UV 695 nm Cr-ruby Artifact of mirror 840 nm IR 840 nm IR

  26. Ruby-1, Namya, CL Ruby-1, Namya, BSE Ruby-3, Namya, BSE Ruby-3, Namya, CL

  27. Painite (CaZrBAl9O18) from Namya, Myanmar – rare gem mineral probably grew during skarn formation  CL shows fine growth layering, implying growth pulses. Inclusions: Cc, Baddeleyite (ZrO2) & Srilankaite (TiZr2O6) Panchromatic

  28. Some Conclusions • CL in zircon, jadeite and garnet of jadeitites is likely due to REE based on enrichment in these rocks. • Zoning structures suggest growth from fluids – for Zircon in jadeitite this implies growth at T = ~ 300°C at P > 1 GPa. • Considerable spectral structure from UV to IR is seen via SEM/CL. • Lots more to do.

  29. Many Thanks to: • Jade & Ruby Helpers: Jinny Sisson, Sorena Sorensen, Carlos Gonzales, Mauricio Chiquin, Will Maze, Bill Larson, George Rossman, Jamie Newman, U Han Htun, Dr. Saw Naung U, Mint Soe • The Founders of the Feast: AMNH, NMNH, Frohlich Charitable Trust, Astor Expedition Fund,Sprague Fund, Michael Scott, & the National Science Foundation.

More Related