The Petoskey Stone Oak land County Earth Science Club May 2018 www.OCESC.com Salt Rock revealSs Rise of Oxygen 2 Summer Club Picnic in July h 2 May 2nd Mark you calendars for Sunday, July A 2-billion-year-old chunk of sea salt n 7:30 PM 22nd for our summer picnic with the a provides new evidence for the MMS club. The 22nd is the fourth n d transformation of Earth’s atmosphere into sunday in July and the picnic will be n Board Meeting an oxygenated environment capable of M f 6:30 held at the same place as last year. supporting ife as we know it. a o The fish hatchery site in Waterford The eveidence for the profound upswing in r r next to the museum. It is a potluck so oxygen comes from salt rocks extracted there will be lots of good food. from a 1.2k mile deep hole in the region of Chicken and ham provided by the Karelia in northwest Russia. These crystals o were left bey hind when ancien seawater u club. There will be stone swaps as evaporated.o The key indication of the r well. Look forward to seeing all of increase inu oxygen came from findind that you there. –Leon Pearson the mineral deposits contained a s surprisinglcy large amount of a component u of seawater known as sulfate, which was Remarkable Twinned Calcite a created when sulfur reacted with oxygen. The Mogok Stone Tract in Myanmar l This is the strongest ever evidence that the (formerly Burma) is one of the e ancient seawater from which those minerls wor ld’s most famous sources of ruby, n precipitated had high sulfate which often forms there in a calcite- concentratdions… This is much higher than Refreshments marble host. Calcite may occur as an previouslya thought. The research will spur inclusion inside the ruby (see website the developmr ent of new models to explain Jackie Presson below for picture). In this stone, the what happes ned after the Great Oxidation Monica Rowe calcite is easy to spot between crossed Event (2.3 Billion years ago). polarizers, which reveal polysynthetic [for complfete article see – twinning planes that “crisscross” the m www.sciencedaily.com/releaes/2018/03/18 crystal. While calcite is a common o m 0322150306.htm inclusion in ruby, this is the clearest r e Thanks to George example of calcite twinning this Brad’s Bench Tips r Matyas and his author has seen. Surrounding the S Reshaping Silicone Wheels helpers for the calcite crystal is a dense, angular nest u Silicone polishing wheels in the Dremel or p goodies in April of exsolved rutile silk as short n Foredom are a great time saver, but often i needles, a typical scene in rubies from need to bed reshaped after being used. c this locality. From The best waay to reshape your wheels is to n https://www.gia.edu/gems- use a fiamyond file or a sparating disk. If gemology/winter-2017-remarkable- i you don’t ,have one and must use a steel twinned-calcite-inclusion c file, sacrif ice the area of the file that is closest to lthe handle, since it is not used w often. -- y i Upcoming Events (events can be found at www.rockngem.com or wwamwa.azmfon.edc.omorg//amutwhorf/Cal/brenadfdar/or)ds Fomr idthet ailed t informatio n, please visit individual club’s website. h t h Upcoming Events (events can be found at www.rockngem.com or www.amfed.org/mwf/Calendar/) For detailed information, please visit individual club’s website. Grinding room at the Waterford Recreation Center- $3 per person, per visit, is the fee. May 4-6: KALAMAZOO, MI Kalamazoo Geological & Mineral Society Annual Show. Fri 4-8 pm; Sat 10 am - 6 pm; Sun 10 am - 5 pm. Kalamazoo County Expo Center, 2900 Lake St. Kzoo May 12-13: TOLEDO, OH Toledo Gem & Rockhound Club Rock/Jewelry Open House. Sat 9:30 am - 4:30 pm; Sun noon - 4 pm. St. James Lutheran Church Gym, 4727 West Sylvania Ave, Toledo. Contact [email protected] May 19-20: ST. JOSEPH, MI Blossomland Gem & Mineral Society Annual Show. Sat 9 am - 6 pm; Sun noon - 6 pm. Lake Michigan Catholic Elementary School, 3165 Washington Ave, St. Joseph. Contact: Nancy Wolff,[email protected] 2018 Refreshments 2018 Programs Please Note: The Club has set a refreshment Jan. reimbursement limit of $50 per meeting. Feb Holiday Banquet Jan. N. Pfauth, L. Sheffer Mar Flint’s Bishop Airport Feb. MAKEUP HOLIDAY BANQUET April Silent Auction- Mar. D. Rathburg, N. Lill May April G. Matyas June May J. Presson & M. Rowe Sept. June Banquet-Potluck Oct. Sept. L. Whitehead Nov Club Member Swap/Sale (Election results) Oct. Dec. Potluck -2nd Wednesday Nov. Dec. Potluck Dec. Club Banquet/Potluck May Birthdays 9 Marie Kahlo 9 Jackie Presson 9 Monica Rowe 11 Bob Albertson 14 Barb Percoulis 24 Lynnette West 26 James McFadden “Don't knock the weather: nine-tenths of the people couldn't start a conversation if it didn't change once in a while." - Kin Hubbard 2 OCESC Board Meeting Minutes for April- will be available at the meeting. OSL Dating of geologic layers -- Optically Stimulated Luminescence (OSL) is a method for measuring doses from ionizing radiation. It is used in at least two applications: * luminescence dating of ancient materials: mainly geological sediments and sometimes fired pottery, bricks etc. * radiation dosimetry, which is the measurement of accumulated radiation dose in health care, nuclear, and building materials in regions of nuclear disaster The method makes use of electrons trapped between the valence and conduction bands in the crystalline structure of certain minerals (most commonly quartz and feldspar). The trapping sites are imperfections of the lattice — impurities or defects. “To carry out OSL dating, mineral grains have to be extracted from the sample. Most commonly these are so-called coarse grains of 100-200 µm or fine grains of 4-11 µm. Occasionally other sizes are used. The difference between radiocarbon dating and OSL is that the former is used to date organic materials, while the latter is used to date minerals. Events that can be dated using OSL are, for example, the mineral's last exposure to sunlight; Mungo Man, Australia's oldest human find, was dated in this manner. It is also used for dating the deposition of geological sediments after they have been transported by air (aeolian sediments) or rivers (fluvial sediments). In archaeology, OSL dating is applied to ceramics: The dated event is the time of their last heating to a high temperature (in excess of 400 °C). Recent OSL dating of stone tools in Arabia pushed the "out-of-Africa" date hypothesis of human migration back 50,000 years and added a possible path of migration from the African continent to the Arabian peninsula instead of through Europe.[Wikipedia] Further reading: https://www.baylor.edu/geology/index.php?id=868084 Above left, rough calcite ‘sunstone’; above right, sunstone found in Alderney wreck “Sunstone” used for navigation before the compass - https://phys.org/news/2011-02-vikings-polarized.html#nRlv (PhysOrg.com) -- The Vikings are said to have been able to navigate with the aid of "sunstones" that allowed them to see the sun on cloudy or foggy days. Now scientists in Hungary and Sweden say the sunstones could have been polarizing crystals. The Vikings were the dominant seafaring explorers of much of Northern Europe and Britain from around 900 to 1200 AD. They were able to navigate their way around the thousands of kilometers of the north Atlantic with great skill and without the help of the magnetic compass, which was not then known in Europe. In the long days of summer at high latitudes they would also have had limited or no views of the stars to help them navigate. Legend has it that these great Scandinavian sailors used a "sólarsteinn," or sunstone, to help them, and stories mentioning the sunstone include the saga of King Olaf and Sigurd, the Icelandic hero. The king asked Sigurd where the invisible sun lay in the cloudy sky and then used a sunstone to check Sigurd’s 3 answer. Danish archaeologist Thorkild Ramskou suggested in 1967 that the sólarsteinn could have been a piece of Icelandic spar, which is calcite in the form of a transparent, polarizing crystal. These crystals are common in Iceland. Other candidates for sunstone include cordierite or tourmaline, both of which are common in Scandinavia. A polarizing crystal allows only light polarized in one direction to pass through, and it appears dark or light depending on its orientation to the polarized light. Sunlight becomes polarized through the scattering of air molecules in the atmosphere, with the line of polarization at a tangent to concentric circles with the sun at their center. Ramskou postulated that the Vikings could have rotated a polarizing crystal to check the direction of polarization and deduce the position of the sun when it was hidden by fog or was just beneath the horizon. Scientists Gábor Horváth from the Eötvös University in Budapest, Susanne Ĺkesson from Lund University, and colleagues around Europe, have been investigating Ramskou’s hypothesis since 2005 because it had never been tested. The researchers began by asking volunteers to identify the position of the sun in 180-degree fisheye lens photographs taken in northern Finland of the sky under twilight, foggy or cloudy conditions. They found the volunteers were inaccurate, making errors of up to 99 degrees. This led Horváth and Ĺkesson to conclude the Vikings were unlikely to have relied on guesses using naked eye observations.