Yooperlights
The article and photos below were copied with permission from Erik Rintamaki. Copy rights fully endorsed.
Radical Rocks links below.
Erik Rintamaki
My discovery of Yooperlites is now official and in publication. If you would like to order a copy they are available for $3 from www.mineralnews.com just click on May 2018
The following is the initial copy of the article. Enjoy and thank you to everyone for all of the support!!
The following is the initial copy of the article. Enjoy and thank you to everyone for all of the support!!
A NEW FIND OF FLUORESCENT SODALITE FROM MICHIGAN’S
UPPER PENINSULA
UPPER PENINSULA
Raymond Laughlin
513 Iron Street
Norway, Michigan 49870
Shawn M. Carlson
245 Jule Lake Road
Crystal Falls, Michigan 49920
Travis A. Olds
Washington State University
School of Mechanical and Materials Engineering
Sloan Hall Room 201
Pullman, Washington 99164
Owen P. Mills
Applied Chemical and Morphological Analysis Laboratory
Michigan Technological University
1400 Townsend Drive
Houghton, Michigan 49931
513 Iron Street
Norway, Michigan 49870
Shawn M. Carlson
245 Jule Lake Road
Crystal Falls, Michigan 49920
Travis A. Olds
Washington State University
School of Mechanical and Materials Engineering
Sloan Hall Room 201
Pullman, Washington 99164
Owen P. Mills
Applied Chemical and Morphological Analysis Laboratory
Michigan Technological University
1400 Townsend Drive
Houghton, Michigan 49931
Back in January 2018, it was brought to the attention of one of us (RL) that a gentleman named Erik Rintamaki was selling pebbles and cobbles of fluorescent syenite that he had collected along the Lake Superior shore in Luce and Chippewa counties of Michigan’s Upper Peninsula, marketing them under the unofficial name “yooperlites”. For those who may be unfamiliar with our geography, denizens of Michigan’s Upper Peninsula are colloquially known as “Yoopers”, a corruption of the abbreviation “U.P.” for Upper Peninsula—ergo yooperlites. Apparently, the fluorescent mineral in these syenites had been visually identified as sodalite by California geologist and fluorescent mineral collector Gabe Reyna. Salting in some details of the discovery provided by Mr. Rintamaki:
“I have a little story that goes with my discovery. About 15 years ago I taught my brother-in-law Jason Klein how to find agates on the shores of Lake Superior north of Newberry. . .and he took to agate picking like no one I've ever seen. He became a rock hound just like me. Well he stumbled across some literature from the Fluorescent Mineral Society about UV lights. And we always dreamed about hitting our beaches at night and seeing the beach turn into a world of fluorescing stones and minerals. So fast forward 15 years and I happened to be on eBay and saw an affordable longwave UV flashlight. So on a whim I ordered one. So in June of 2017 I left for the beach. . .at 4:00 a.m. I got to the beach just in time to use my cheap 3 LED longwave UV flashlight and found 2 very small Yooperlites about the size of a dime. I went 4 more times and only found half a dozen stones. Then I upgraded to a 100 LED UV torch and that’s when the fun began in the fall of 2017. My largest find so far was over 5 pounds. Now I have upgraded even further to Convoy S2+UV and a shortwave lamp. So I hope to open even more secrets of our Lake Superior beaches.”
--E. Rintamaki, written comm., February and March 2018.
To our knowledge, sodalite has not been reported from Michigan before; no mention of it is made in The Mineralogy of Michigan (Heinrich, 1976), Mineralogy of Michigan by E. Wm. Heinrich (Robinson, 2004), or in Mineralogy of Michigan Update (Robinson and Carlson, 2013). In order to study this occurrence further, our research team purchased several kilograms of sodalite-bearing syenite from Mr. Rintamaki for analysis. Upon receipt, we observed that the clasts do indeed resemble syenite at first glance and most likely are; however, we note here that we have not conducted any whole-rock analyses to classify these rocks chemically (TAS) nor have we performed any thin section point-counts to classify them via modal mineralogy, as our primary interest is with the fluorescent sodalite and not with formal igneous rock-type classification. Expressed differently, all or most of these rocks are probably some type of syenite but that we have not performed the necessary tests to confirm this.
Mineralogy. The mineral reported as sodalite does indeed display a strong hackmanite-like fluorescence in response to longwave UV illumination (Figures 1 and 2). Examined under incandescent illumination and binocular stereozoom microscope, the mineral is generally a very pale gray but hints of yellow and teal are observed. And it is translucent although this is probably due to heavy fracturing, as small unfractured domains appear transparent. Examined via petrographic microscope the material possesses a refractive index between 1.480 and 1.490 (consistent with sodalite) and appears isotropic in crossed polars (Figure 3). Preliminary SEM/EDS analyses conducted at Michigan Technological University showed only Na, Al, Si, Cl and O in the mineral’s spectrum. Sulfur was sought but not noted; we believe this element is present but at levels below EDS detection limits. Microscopic studies were conducted using a Kyowa SDZ-P binocular stereozoom microscope and a Kyowa ME-POL2 petrographic and ore microscope equipped with a Supper spindle stage. EDS spectra were obtained at Michigan Technological University on a JEOL 6400 tungsten-source SEM equipped with a 4pi Analysis (Inc.) ultrathin window EDS detector and operated at 20 kV. WDS analyses were provided by the Saskatchewan Research Council on a Cameca SX-100 LaB6 microanalyzer operated at 15 kV, using standards from Structure Probe (Inc.), the Smithsonian Institution, and Astimex Standards (Ltd.)
We therefore concur with Rintamaki and Reyna that this fluorescent mineral is indeed sodalite, and that this is the first verified sodalite documented from the state of Michigan. Our congratulations and thanks to the discoverers for bringing this find to our attention.
“I have a little story that goes with my discovery. About 15 years ago I taught my brother-in-law Jason Klein how to find agates on the shores of Lake Superior north of Newberry. . .and he took to agate picking like no one I've ever seen. He became a rock hound just like me. Well he stumbled across some literature from the Fluorescent Mineral Society about UV lights. And we always dreamed about hitting our beaches at night and seeing the beach turn into a world of fluorescing stones and minerals. So fast forward 15 years and I happened to be on eBay and saw an affordable longwave UV flashlight. So on a whim I ordered one. So in June of 2017 I left for the beach. . .at 4:00 a.m. I got to the beach just in time to use my cheap 3 LED longwave UV flashlight and found 2 very small Yooperlites about the size of a dime. I went 4 more times and only found half a dozen stones. Then I upgraded to a 100 LED UV torch and that’s when the fun began in the fall of 2017. My largest find so far was over 5 pounds. Now I have upgraded even further to Convoy S2+UV and a shortwave lamp. So I hope to open even more secrets of our Lake Superior beaches.”
--E. Rintamaki, written comm., February and March 2018.
To our knowledge, sodalite has not been reported from Michigan before; no mention of it is made in The Mineralogy of Michigan (Heinrich, 1976), Mineralogy of Michigan by E. Wm. Heinrich (Robinson, 2004), or in Mineralogy of Michigan Update (Robinson and Carlson, 2013). In order to study this occurrence further, our research team purchased several kilograms of sodalite-bearing syenite from Mr. Rintamaki for analysis. Upon receipt, we observed that the clasts do indeed resemble syenite at first glance and most likely are; however, we note here that we have not conducted any whole-rock analyses to classify these rocks chemically (TAS) nor have we performed any thin section point-counts to classify them via modal mineralogy, as our primary interest is with the fluorescent sodalite and not with formal igneous rock-type classification. Expressed differently, all or most of these rocks are probably some type of syenite but that we have not performed the necessary tests to confirm this.
Mineralogy. The mineral reported as sodalite does indeed display a strong hackmanite-like fluorescence in response to longwave UV illumination (Figures 1 and 2). Examined under incandescent illumination and binocular stereozoom microscope, the mineral is generally a very pale gray but hints of yellow and teal are observed. And it is translucent although this is probably due to heavy fracturing, as small unfractured domains appear transparent. Examined via petrographic microscope the material possesses a refractive index between 1.480 and 1.490 (consistent with sodalite) and appears isotropic in crossed polars (Figure 3). Preliminary SEM/EDS analyses conducted at Michigan Technological University showed only Na, Al, Si, Cl and O in the mineral’s spectrum. Sulfur was sought but not noted; we believe this element is present but at levels below EDS detection limits. Microscopic studies were conducted using a Kyowa SDZ-P binocular stereozoom microscope and a Kyowa ME-POL2 petrographic and ore microscope equipped with a Supper spindle stage. EDS spectra were obtained at Michigan Technological University on a JEOL 6400 tungsten-source SEM equipped with a 4pi Analysis (Inc.) ultrathin window EDS detector and operated at 20 kV. WDS analyses were provided by the Saskatchewan Research Council on a Cameca SX-100 LaB6 microanalyzer operated at 15 kV, using standards from Structure Probe (Inc.), the Smithsonian Institution, and Astimex Standards (Ltd.)
We therefore concur with Rintamaki and Reyna that this fluorescent mineral is indeed sodalite, and that this is the first verified sodalite documented from the state of Michigan. Our congratulations and thanks to the discoverers for bringing this find to our attention.
Although no mention of syenite is made in Susan Robinson’s artistic study Is this an Agate? An Illustrated Guide to Lake Superior’s Beach Stones Michigan (Robinson, 2001) it has been our experience that syenite clasts are not that rare in Michigan, and can be found along many Lake Superior beaches as well as in gravel pits within Upper Michigan’s interior. Perhaps this clast lithology has been traditionally underestimated because of it being misidentified as granite and thus dismissed by collectors as not very interesting. Although there are some small syenite bodies in Upper Michigan’s Marquette County, to the west of this study area, we believe that it is unlikely that Rintamaki’s sodalite-bearing syenite clasts are locally-sourced. It is more probable that the bedrock source of this material is located in Canada, specifically the Coldwell Alkaline Complex in Ontario, and that fragments of that complex were transported to their approximate present-day location by continental glaciation, further slightly moved, concentrated, and somewhat wave-polished by Lake Superior. Indeed, the presence of minor orange-red natrolite (alteration of nepheline) in these clasts argues strongly for a Coldwell Complex origin (Mitchell and Platt, 1982).
Approximately 187 valid mineral species were known to occur in Michigan in 1976 when Heinrich published the first edition of our state’s geographic mineralogy. Today, there are about 383 minerals known in Michigan, more than double. Yet despite this obvious advancement, the fact that discoveries like this fluorescent sodalite can still be made—a mineral not previously confirmed in Michigan but now known to occur in kilogram quantities along Lake Superior beaches—suggests that the mineralogy of our state is significantly under-studied, and that hundreds of minerals new to Michigan (plus possible brand new species for the world) await discovery here. We warmly encourage future collectors and researchers to go out and discover them.
ACKNOWLEDGMENTS
We thank Erik Rintamaki for making us aware of this discovery, and Gabe Reyna for mineral identification. Vancouver Petrographics Ltd. are acknowledged for preparing polished thin sections, and Steven Creighton of the Saskatchewan Research Council is credited for providing microprobe analyses. Finally, Vicky Underhill, Audrey E. Smith, and Mark Smyk (Ontario Geological Survey) are thanked for their helpful reviews and comments.
REFERENCES
Carlson, S.M. and T.A. Olds. In prep. Mineralogy of Michigan update, discoveries and new developments for
the period 2013-2019.
Heinrich, E.W. 1976. The mineralogy of Michigan. Michigan Department of Natural Resources, Geological
Survey Division, bulletin 6.
Mitchell, R.H. and R.G. Platt. 1982. Mineralogy and petrology of nepheline syenites from the Coldwell Alkaline
Complex, Ontario, Canada. Journal of Petrology 23 (2): 186-214.
Robinson, G.W. 2004. Mineralogy of Michigan by E. W. Heinrich—Revised and updated. Houghton, MI: A.E.
Seaman Mineral Museum, Michigan Technological University.
Robinson, G.W. and S.M. Carlson. 2013. Mineralogy of Michigan update. Houghton, MI: A.E. Seaman Mineral
Museum, Michigan Technological University (on-line document formerly available at www.museum.mtu.edu).
Robinson, S. 2001. Is this an agate? An illustrated guide to Lake Superior’s beach stones Michigan. Hancock, MI:
Book Concern Printers.
FIGURE CAPTIONS
Figure 1. A collection of “yooperlites” (syenite clasts containing fluorescent sodalite) collected from Lake Superior beaches in Chippewa and Luce counties, Upper Peninsula of Michigan. No dimensional scale but these specimens collectively weigh about one pound, as indicated on the paper note. LWUV LED illumination, Erik Rintamaki photograph.
Figure 2. Close-up of fluorescent sodalite. LWUV LED illumination, FOV approximately 4.0 mm, Travis A. Olds photograph. Although the fluorescent intensity of this Michigan sodalite is best described as moderate when illuminated by older-model Hg-vapor sources like the well-known portable 6-watt Mineralight® lamp, the fluorescence is quite brilliant in response to modern powerful multi-LED ultraviolet flashlights.
Figure 3. Polished thin section, showing potassium feldspar laths (K) in a matrix of isotropic sodalite (S) with minor undifferentiated amphibole (A). Tiny inclusions within amphibole are nepheline (WDS-verified), another mineral never officially reported from Michigan before now (Carlson and Olds, in prep). Crossed polars with gypsum accessory plate; FOV 1.5 mm. Shawn M. Carlson photograph.
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