Mineralogy Faqs

Popular Mineralogy Interesting mineralogy and earth science for the amateur mineralogist and serious collector - #16

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The Flying Dragons of The Carboniferous

by Andrew A. Sicree ______

Just how big can a bug get? tooth, a reference to the toothy jaws found in most

adult dragonflies). Although Meganeuropsis The biggest insect ever to roam the earth didn’t looked much like a huge version of the modern- do much roaming – it flew! We joke about day dragonfly, there are some important mosquitoes big enough to carry off pets and small differences between the two groups. Dragonflies children, but way back in the Carboniferous coal of both Odonata and Protodonata strong spiny swamps the dragonflies were much bigger than legs and toothy jaws, which facilitate the capture the biggest baddest bug beating its wings down in of prey, but the Protodonata were, of course, the bayous today. enormous compared to modern-day dragonflies.

Meganeura monyi is the name that The jaws of the protodonates were larger than paleoentolomogists (scientists who study fossil those of modern dragonflies and their legs were insects) have given to the biggest insect ever to stronger and longer. Their forewings are usually have roamed – or rather flown – the Earth. slightly longer and a bit thinner than their Meganeura monyi was a giant version of a hindwings. These early dragonflies lacked a wing modern dragonfly and had a wingspan greater notch (the nodus) and the pterostigma (the blood- than 30 inches (75 cm) across. By comparison, rich colored patch on a dragonfly’s wing). the largest modern-day dragonfly is Anax Because of the differences between the two strenuous (the Giant Hawaiian Darner or the groups, some authors have suggested that the term “giant dragonfly” be replaced with “griffinfly.” Giant Hawaiian Dragonfly) which has a wingspan up to 7.5 inches (19 cm). Meganeuropsis Insects of the order Odonata first make their permiana is another early dragonfly, found in the appearance in the Triassic (245-208 years ago); early Permian. At 28 inches (71 cm) its wingspan the Protodonata went extinct in the Triassic about rivals that of Meganeura monyi. These bigger- the same time as the earliest dinosaurs appear. than-most-birds dragonflies were predatory, Why so big? capturing other insects in flight and perhaps feeding on small amphibians. Scientists continue to debate the causes of

gigantism among ancient insects. One theory The oldest dragonflies states that insect body size is limited by the way Paleoentolomogists report that the oldest an insect gets oxygen. It is thought that insects known dragonfly fossils have been recovered get oxygen by diffusion through their tracheal from Upper Carboniferous (i.e., Pennsylvanian) tubes rather than by “breathing” air in and out. sedimentary rocks in Europe. The Carboniferous Thus, the theory postulates, insects were able to Period stretched from about 360 million years ago grow much larger in the Carboniferous because to about 286 million years ago. It is divided the atmosphere had higher levels of oxygen than (especially in North America) into the the present-day 20%. Other entomologists Mississippian (the Early or Lower Carboniferous contend that insects really do breathe (by means – approximately 360-320 million years ago) and of rapid expansion and contraction of their Pennsylvanian (Late or Upper Carboniferous – tracheal tubes) and thus the atmosphere of the about 320-286 million years ago) periods. Carboniferous need not have been oxygen-rich to support gigantic insects. Meganeuropsis permiana and other now- extinct ancestral dragonflies are classified into the Dragonfly fossils in Appalachia? extinct order Protodonata. Modern-day dragonflies belong to the order Odonata (the Because dragonflies lived near water, one name is taken from “odonto-,” the Greek word for might suspect that they would be likely candidates

©2008, Andrew A. Sicree, Ph.D., [email protected] ~ 9-08-1 ~ Please do not reproduce or extract without permission for fossilization. Paleontology books depict In the Eastern U.S., however, only a few reconstructed dioramas featuring giant dragonflies fossils of Protodonata are known. In 1889, a buzzing through the ancient coal swamps. It is specimen of Paralogus aeschnoides was found in not unusual to find ferns and other plant fossils by Upper Carboniferous rocks near Silver Spring, the ten of thousands preserved in the coal and East Providence, Rhode Island. shale of Appalachian coal mines. Why don’t we A wing fragment in black shale, attributed to find more dragonfly fossils among all these ferns? the species Palaeotherates pennsylvanicus, was One problem may be that, being predators at collected in 1887 from Coxton, one mile north of the top of the insect food chain, large dragonflies Pittston, Pennsylvania. It appears that the weren’t all that common. Another consideration specimen was taken from the Upper Pottsville is that, because of their large but somewhat Formation. A specimen of Tupus durhami was delicate bodies, it would be unusual for an entire collected in 1939 from the roof shale over the No. dragonfly to be preserved intact. Indeed, most 4 Coal at a coal mine in Catoosa (Durham specimens of Carboniferous and Permian fossil Quadrangle), Georgia. Interestingly, it appears dragonflies are known from wing fragments few that this fossil came from the Pottsville Series of of which are even complete wings. Body fossils Georgia and is of Lower Pottsville age – this are even rarer. corresponds approximately to the lower portions of the Pottsville Formation in Pennsylvania. Another factor may be a matter of who is looking for them. Modern coal mining is heavily A more recent in Pennsylvania is that of mechanized and the miner has little opportunity to Palaeothertes analis, which is preserved at the climb down out of his haul truck and search for William Penn Museum in Harrisburg. This fossils. The best hope for finding dragonfly specimen came from the underclay of the Buck fossils is to go to sites at which the rocks are of Mountain #5 anthracite, part of the Allegheny the correct ages and at which fossils of plants are Series. It was found in a strip mine located 400 preserved. Even more important would be to meters eat of benchmark 1271 on the St. Clair- identify sites from which other, smaller fossil Mahoney City Road, in Blythe Township, insects have been recovered. Schuylkill County, Pennsylvania.

______To find a fossil dragonfly

Dragonfly fossils were first recognized in Ideal vs. Real Formulas in Minerals Europe. In 1880, fossils of Meganeura monyi were discovered in the Stephanian Coal Measures Mineralogy texts often accompany their near Commentry, France. descriptions of each mineral with a chemical formula. Articles in magazines such as The In North America, protodonatan fossils have Mineralogical Record may also give formulae for been found in rocks from the Grand Canyon in minerals. And mineral lists such as Fleischer’s Arizona. Many important fossil dragonflies have Glossary of Mineral Species (the 10th Edition, been found in the Permian strata of Kansas and released in 2008, authored by Malcolm Black and Oklahoma. The largest complete insect wing ever Joseph A. Mandarino) give mineral formulae, too. recovered is of Meganeura americana, found in The observant collector will notice that sometimes Oklahoma in 1940; it can be seen at the Harvard there are differences between the ways different Museum of Natural History. literature sources report formulae for the same Odonata fossils are more common. The have mineral. been found in the Upper Triassic in Italy, and the This may be because the older source is famous Solnhofen lithographic limestones of reporting the mineral formula as it was known Upper Jurassic age in Germany. China produces originally, while another source is reporting a dragonfly fossils, and some are also found in the more-accurate formula based on later data. Lower Cretaceous Crato Formation of northeast Sometimes, there are perfectly valid, but different, Brazil. This is not a comprehensive list; many ways to write a mineral’s formula. For instance, other localities are known. John Sinkankas’ Mineralogy gives HFeO2 as the

©2008, Andrew A. Sicree, Ph.D., [email protected] ~ 9-08-2 ~ Please do not reproduce or extract without permission formula for the common mineral goethite. Other Encounters of the Third Kind.” Naturally curious, sources use FeO(OH). Note that both give the I stopped too, expecting maybe to see a UFO. No same ratios of Fe, H, and O. UFO’s were visible, but what I did see was a

But discrepancies can also be because one wavy pulsing curtain of deep blue and purple – the Northern Lights. literature source is reporting the “ideal” chemical formula while another is reporting the actual What I didn’t know at the time was that I chemical formula for the mineral as found in should’ve hauled out my freshly collected calcite nature. One example of this may be seen by and willemite specimens (I had been at a night dig examining the case of franklinite. Franklinite is at the Sterling Hill Mine in Odgensburg, NJ – a

“zinc iron oxide” and the ideal formula is ZnFe2O4 famous locality for fluorescent minerals) and In this formula, zinc is present as Zn2+ and iron as checked to see if they glowed under the aurora.

3+ Fe , while oxygen atoms have a “minus two” The aurora is created when “energetic” 2- charge (i.e. O ). Electrical charges are balanced particles from the Sun smash into the Earth’s in this formula. Four oxygens in the minus two upper atmosphere. Mostly, these particles are the state give a total of eight negative charges. Two nuclei of hydrogen atoms (i.e., protons) and irons in the three plus state give a total of six electrons. When they hit gas molecules in the positive charges, and two more from the zinc ion upper reaches of the Earth’s atmosphere (above bring the total to eight positive charges. Thus, the 80 kilometers or 50 miles) they knock off mineral is electrically neutral. electrons. As the electrons recombine with the An actual specimen of franklinite may contain gas molecules, they give off light. a substantial amount of manganese (Mn). How The colors you see are a function of the energy does that fit into the picture? In such a case, the of the solar particles. If the incoming particles formula is closer to (Zn,Mn,Fe)(Fe,Mn)2O4. have energies of a few hundred electon volts, they Putting the first three elements in the first set of don’t get below altitudes of about 200 km (125 brackets indicates that some of each of those miles) and they produce a red aurora. Solar 2+ 2+ 2+ elements (as Zn , Mn or Fe ) is occupying the particles with energies of about 1 kiloelectron volt 2+ position that Zn held in the ideal formula. (KeV) create auroras that are greenish-yellow. Likewise, either iron or manganese may occupy And their more-energetic buddies, those with the site held by iron in the ideal formula. Note energies around 10KeV, penetrate deeper into the that the iron and manganese must be in the “three Earth’s atmosphere (below 100 km or 63 miles) 3+ 3+ plus” state (as Fe or Mn ) to produce an and stir up auroral colors that can be deep purple. electrically-neutral mineral. This actual formula gives us more information than the ideal formula If you get even more powerful solar particles, does. It tells us, for instance, that both iron and with energies above 100 KeV, the auroral manganese are present in franklinite as both “plus emissions will occur in the ultraviolet. In theory then, one should be able to get a tan at night in the two” and “plus three” ions. ©2008, Andrew A. Sicree, Ph.D. winter above the Artic Circle if the auroras are ______strong. In reality however, the auroral ultraviolet light is probably too weak to expect to be able to Weird Geology observe fluorescence in even the brightest fluorescing specimens. Still, it is an experiment to Ultraviolet Auroras try one wintery night if you are in Point Barrow, The Northern Lights or the aurora borealis are Alaska, and happen to have a good Sterling Hill an eerie, beautiful phenomenon best observed in willemite with you!

Alaska and northern Canada, but also visible Ref: Strangeway, R. J., “How do auroras form?” Physics much further south. Driving west from New York Today, p. 68-69, July 2008 City on I-80 late one night, I was surprised to ©2008, Andrew A. Sicree, Ph.D. encounter a large number of cars parked along the Dr. Andrew A. Sicree is a professional mineralogist and geochemist roadside with the drivers standing outside staring residing in Boalsburg, PA. This Popular Mineralogy newsletter supplement may not be copied in part or full without express to the north. It looked like a scene from “Close permission of Andrew Sicree. Write P. O. Box 10664, State College PA 16805 (814) 867-6263 or email [email protected] for more info.

1 2 3 4 5 6 7 8 9 10 11 12 13 Some Fossils 14 15 16

ACROSS 17 18 1 extinct three-lobed arthropod 19 20 21 10 shape of horn coral fossil 14 springs in desert regions 22 23 24 25 26 27 28 15 ____ Linda 29 30 31 32 33 16 chocolate cake dessert 34 35 36 17 multi-hulled boat 18 common shell fossils 37 38 39 40 19 original equipment (ab) 41 42 43 44 20 the way 45 46 47 48 21 dysprosium 22 you and I 49 50 51 52 23 state of Ruggles Mine 53 54 55 56 25 layer containing fossils 57 58 59 60 61 62 63 29 related to fossil sharks 31 rotate about vertical axis 64 65 66

33 not quite micro 67 68 34 Much __ About Nothing 35 state with lots of fossils 41 can be found a fossils 36 who Bugs always talks to DOWN 43 where the scientists are 37 type of sandwich 1 map used for fossil hunts 44 not a guy 38 girl’s name 2 what Archaeopteryx is 46 upper left state 39 great bird 3 on film 48 ancient fossil tree 40 where Songo Pond is 4 fossils from trees 50 gives fossil to museum 41 ___ you dad 5 osmium 54 famous mineralogist 42 to close a mine shaft 6 not at all well 56 Yugo despot 44 Green River fossil fish 7 we thought you was a __ 57 sine ___ non 45 excited atoms 8 TV awards 58 cavemen say this 47 ___ Sack 9 Special Air Service 59 Tokyo airport code 48 Greek Earth goddess 10 ___ Guevara 60 Confederate 49 fossil sea lily 11 not fossil eggs 61 Royal Shakespeare Co.

51 halogen from sea 12 hockey league 63 knock 66 art. intelligence

52 big coal state 13 Titan of the dawn LAST MONTH’S SOLUTION: Africa 53 optometrist’s right eye 18 grand ditch T O R B E R N I T E GNUS 55 period of geologic time 22 yellow stone state EM E R Y A D I T FIAT 56 drink with jam and bread 24 what donkey says RA M A M A LACHITES MN Z I A YR R 57 our current era 26 to run crazy I V I L A ACACIAS 62 short Kristofer, Kristine 27 international group NA I L A B S ATMO 64 ____ as a bug 28 turned to stone (British) AD Z S W A T EVE U 65 more time periods 30 adjust (ab) TO D E I O ONE FT I C R T NEXT OOH 66 layered quartz 32 thin waisted insects OB O E EPI GIGA 67 what Charlie Chan says 35 what squid makes N A M I B I A AD UL F 68 two-shelled mollusk 36 how fossil was found O V U ELI MR 38 association C E R U S S I T E S NISI AT O M E L EV XEBEC 39 ____ Hepburn R A S P C A SABLANCA 40 ___ West – a lifejacket