The Microscope – Volume 65, Fourth Quarter 2017
IN THIS ISSUE
On the cover
A stereographic projection of the results from a spindle stage input for a single crystal using EXCELIBR, by Stevens and Gunter of the University of Idaho. See EXCELIBR: An Excel Spreadsheet for Solving the Optical Orientation of Uniaxial and Biaxial Crystals, page 147. (Image courtesy of C.J. Steven and M.E. Gunter.)
Editorial | A Modern Approach to Optical Crystallography with the PLM
Gary J. LaughlinThe Microscope 65:4, p. ii, 2017https://doi.org/10.59082/CCIN8675
Excerpt: There is recent resurgence in the study of crystals through the use of the spindle stage — a rather simple accessory consisting of a flat sturdy base (homemade from metal, hard plastic, or poster board), a protractor to indicate the angular degrees of the spindle’s rotation, the spindle or needle onto which is glued the single crystal to be studied, and a glass microscope slide dock with a well to hold the refractive index liquid — positioned on the polarized light microscope.
EXCELIBR: An Excel Spreadsheet for Solving the Optical Orientation of Uniaxial and Biaxial Crystals
C.J. Steven and M.E. Gunter
The Microscope 65:4, pp. 147–152, 2017https://doi.org/10.59082/KLWH2345
Abstract: The polarized light microscope remains the single most useful tool in identifying minerals. Using a spindle stage, a user can orient a crystal’s principle refractive index (RI) vectors, parallel to the lower polarizer, and in turn, observe its RI. Finding the principle RI vectors is accomplished by using either conoscopic methods, or more simply, using extinction data as inputs in the program EXCALIBR, which was developed by Bloss and Riess in 1973. The use of EXCALIBR has major advantages over conoscopic methods, but it is hindered by interface and compatibility issues.
Presented here is a Microsoft Excel spreadsheet named “EXCELIBR,” which performs similar functions to EXCALIBR, including solving for the optical orientation of biaxial or uniaxial minerals using extinction data. Using Excel as the interface, EXCELIBR is accessible, familiar, and versatile for the user. The program is useful for preliminary screening of a crystal for X-ray studies, optical characterization of minerals, and rapid mineral identification. Included with its crystal-orienting calculations are tabs for double variation and RI modeling, similar to those in Opt_cal, a program that calculates miscellaneous optical properties of minerals.
Abstract: The polarized light microscope remains the single most useful tool in identifying minerals. Using a spindle stage, a user can orient a crystal’s principle refractive index (RI) vectors, parallel to the lower polarizer, and in turn, observe its RI. Finding the principle RI vectors is accomplished by using either conoscopic methods, or more simply, using extinction data as inputs in the program EXCALIBR, which was developed by Bloss and Riess in 1973. The use of EXCALIBR has major advantages over conoscopic methods, but it is hindered by interface and compatibility issues.
Presented here is a Microsoft Excel spreadsheet named “EXCELIBR,” which performs similar functions to EXCALIBR, including solving for the optical orientation of biaxial or uniaxial minerals using extinction data. Using Excel as the interface, EXCELIBR is accessible, familiar, and versatile for the user. The program is useful for preliminary screening of a crystal for X-ray studies, optical characterization of minerals, and rapid mineral identification. Included with its crystal-orienting calculations are tabs for double variation and RI modeling, similar to those in Opt_cal, a program that calculates miscellaneous optical properties of minerals.
The Microscope Past: 25 Years Ago | Variation in Optical Class and Optical Orientation: The Rule, Not the Exception
Mickey E. GunterThe Microscope 65:4, pp. 153–158, 2017
Originally published in The Microscope, Vol. 40, First Quarter, pp. 81–92, 1992.
Abstract: The crystal symmetry of minerals, isotropic vs. anisotropic (and biaxial vs. uniaxial) can be determined by observations with a polarized light microscope. However, in certain instances, minerals can exhibit apparent optical symmetry higher than the crystal system they belong to. For example, the two refractive indices of a uniaxial mineral become equal, making the mineral appear isotropic and thus belong to the cubic crystal system. Usually, any change in optical class is accompanied by a change in optical orientation. These unusual optical coincidences are often observed when mineral groups are studied very carefully, using both optical and X-ray methods to track changes in optical orientations and refractive index for single crystals in solid solution series. However, chemistry is not the only variable that causes a mineral to change its optical class and optical orientation; these changes can also be caused by dispersion, temperature, and structural state.
Critical Focus | Still Waiting for Cures After All These Years
Brian J. Ford
The Microscope 65:4, pp. 159–169, 2017https://doi.org/10.59082/JIQU4829
Excerpt: What is our principle ally in medicine? Body scanners? Antibiotics? That friendly physician whose charm and charisma settles the soul? A big budget from your medical insurance? None of these. It is something that doesn’t cost a cent, can make decisions that elude the cleverest doctor, carries out meticulous tasks no robot could replicate, and with which you come already equipped — the living cell. Now we are harnessing the magical capacity of stem cells, the most miraculous of all cell types. So far, we have done little to capture their potential, but it is the study of stem cells that is set to revolutionize medicine. We take a lot of credit for our medical expertise. Most of it we don’t deserve. We say how well we can heal a sore, close a wound, mend a bone, treat a trauma; but usually the human doctor plays a minor role. Our main task is not to bring about the miracle through intellectual ingenuity, but to harness the ability of stem cells to do the work for us.
Microcrystal Tests for the Identification of Illicit Drugs: d-Methamphetamine and and dl-Methamphetamine
Kelly M. Brinsko, M.S.; Dean Golemis, B.A.; Meggan B. King, B.S.; Gary J. Laughlin, Ph.D.; and Sebastian B. Sparenga, M.S.
The Microscope 65:4, pp. 171–186, 2017
https://doi.org/10.59082/DNVL2895
Abstract: The Microscope is publishing monographs from McCrone Research Institute’s A Modern Compendium of Microcrystal Tests for Illicit Drugs and Diverted Pharmaceuticals (4th revision: September 13, 2021), which contains 19 different drugs and their microcrystal test reagents. This issue includes monographs for the following drug/reagents:
• d-methamphetamine/gold chloride• d-methamphetamine/platinum chloride• dl-methamphetamine/gold chloride• dl-methamphetamine/platinum chloride
The previous set of monographs were published in issue 65:3 (2017): heroin with mercuric chloride and mercuric iodide, hydrocodone with platinum bromide, hydromorphone with platinum bromide and sodium nitroprusside, MDMA with gold chloride, methadone with mercuric chloride and mercuric bromide, and methylphenidate with picric acid and lead iodide solution. Monographs for remaining microcrystal tests will be published in subsequent issues.
The previous set of monographs were published in issue 65:3 (2017): heroin with mercuric chloride and mercuric iodide, hydrocodone with platinum bromide, hydromorphone with platinum bromide and sodium nitroprusside, MDMA with gold chloride, methadone with mercuric chloride and mercuric bromide, and methylphenidate with picric acid and lead iodide solution. Monographs for remaining microcrystal tests will be published in subsequent issues.
Author and Subject Indexes: Volume 65, 2017
The Microscope 65:4, pp. 187 - 190, 2017
Correction | “Analysis of Amphibole Asbestos in Chrysotile-Containing Ores and a Manufactured Asbestos Product”
The Microscope 65:4, p. 190, 2017
https://doi.org/10.59082/IMQQ6395
The article, “Analysis of Amphibole Asbestos in Chrysotile-Containing Ores and a Manufactured Asbestos Product” by J.R. Millette, A. Harmon, P. Few, W.L. Turner Jr., and W.R. Boltin, (The Microscope, Volume 57, 1st Quarter, pp. 19–22, 2009, DOI forthcoming), contains the following two errors:
• Page 19, column 2: In the Introduction section, change “sepentinite” to “serpentinite.”• Page 20, column 2: In the Analysis Methods section, change “0.5 mm” to “0.5 μm.”
The Microscope regrets the errors.
Ammonium Nitrate, Form II
Andrew M. Bowen — U.S. Postal Inspection Service
The Microscope 65:4, p. 192, 2017
Ammonium nitrate has five polymorphs (that we know of), each with its own temperature stabilityrange. The polymorphic form in this photomicrograph is Form II, the “room temperature” stableform in the range from –16° to 32° C. Form II ammonium nitrate is orthorhombic and very highlybirefringent (0.224) as exhibited here in this fusion preparation photographed with the polarizedlight microscope at ca. 25° C, crossed polars, 100×.
Ammonium nitrate has five polymorphs (that we know of), each with its own temperature stabilityrange. The polymorphic form in this photomicrograph is Form II, the “room temperature” stableform in the range from –16° to 32° C. Form II ammonium nitrate is orthorhombic and very highlybirefringent (0.224) as exhibited here in this fusion preparation photographed with the polarizedlight microscope at ca. 25° C, crossed polars, 100×.
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