Al-Hussaini, A., A. Koeshidayatullah, and K. Al-Ramadan. 2015. Formation conditions and diagenetic evolution of sand roses in clastic sabkhas along the Arabian Gulf Coastal Region, Eastern Saudi Arabia. Geological Quarterly 59(1): 71-78.
Allen, H. M., D. G. Bailey, and B. J. Tewksbury. 2014. Pseudomorphed mineral aggregates of the Khoman Chalk, Western Desert, Egypt. GSA abstract.
Aso, E., T. J. Gisbert, and B. V. Garcés. 1992. Type septaria-cone in cone nodules in the Stephano-Permian of the Catalan Pyrenees. Carbonates and Evaporites 7(2): 132-139.
Astin, T. R. 1986. Septarian crack formation in carbonate concretions from shales and mudstones. Clay Minerals 21: 617-631.
Baratoux, D., and W. U. Reimold. 2016. The current state of knowledge about shatter cones: Introduction to the special issue. Meteorics & Planetary Science 51(8): 1-46.
Bell, H. S. 1940. Mud balls: Their origin, properties, and role in sedimentation. Journal of Geology 48(1): 1-31.
Bennett, M., P. Doyle, and A. E. Mather. 1996. Dropstones: Their origin and significance. Palaeogeography, Palaeoclimatology, Palaeoecology 121: 331-339.
Bischoff, J. L., et al. 1993. Ikaite precipitation by mixing of shoreline springs and lake water, Mono Lake, California, USA. Geochimica et Cosmochimica Acta 57: 3855-3865.
Boggs, Jr., S. 1975. “Glendonites” from Oregon and Washington. The Ore Bin 37(6): 89-103.
Bourli, N., et al. 2021. Comparison between siliceous concretions from the Ionian Basin and the Apulian Platform Margins (Pre-Apulian Zone), Western Greece: Implications of differential diagenesis on nodules evolution. Minerals 11(890): 1-28.
Buchner, E., V. J. Sach, and M. Schmieder. 2021. Sand spikes pinpoint powerful palaeoseismicity. Nature Communications 12(6731): 1-11.
Burns, R. G., and V. M. Burns. 1975. Mechanism for nucleation and growth of manganese nodules. Nature 255(May 8): 130-131.
Burt, F. A. 1928. Melikaria: Vein complexes resembling septaria veins in form. Journal of Geology 36(6): 539-544.
Calaforra, J. M., P. Forti, and A. Fernandez-Cortes. 2008. Speleothems in gypsum caves and their paleoclimatological significance. Environmental Geology 53: 1099-1105.
Carman, M. R. 1989. The monster of Illinois: Paleontology and politics. Rocks & Minerals 64(1): 36-41.
Case, D. H., et al. 2015. Methane seep carbonates host distinct, diverse, and dynamic microbial assemblages. mBio 6(6): 1-12.
Chan, M. A., et al. 2007. Models of iron oxide concretion formation: Field, numerical, and laboratory comparisons. Geofluids 7: 1-13.
Chan, M. A., and W. T. Parry. 2002. Rainbow of Rocks. Public Information Series 77. Utah Geological Survey.
Chan, M. A., B. B. Bowen, and W. T. Parry. 2005. Red rock and red planet diagenesis: Comparison of Earth and Mars concretions. GSA Today 15(8): 4-10.
Ciampaglio, C. N., et al. 2006. Phylogenetic affinities and taphonomy of Brooksella from the Cambrian of Georgia and Alabama, USA. Palaeoworld 15: 256-265.
Clements, R., and S. Gabbott. 2022. Exceptional preservation of fossil soft tissues. eLS 2(12): 1-10.
Clements, T., M. Purnell, and S. Gabbott. 2019. The Mazon Creek Lagerstätte: A diverse late Paleozoic ecosystem entombed within siderite concretions. Journal of the Geological Society 176: 1-11.
Cox, M. R., and K. R. Evans. 2007. Geologic Map of the Vista 7.5' Quadrangle, St. Clair County, Missouri. OFR-07-101-GS. Rolla, Missouri: Missouri Dept. of Natural Resources.
De Boever, E., et al. 2008. The Pobiti Kamani area (Varna, NE Bulgaria) – Study of a well-preserved paleo-seep system. Review of the Bulgarian Geological Society 69(1-3): 61-68.
De Boever, E., et al. 2009. Controlling factors on the morphology and spatial distribution of methane-related tubular concretions – Case study of an Early Eocene seep system. Marine and Petroleum Geology 26: 1580-1591.
De Lurio, J. L., and L. A. Frakes. 1999. Glendonites as a paleoenvironmental tool: Implications for early Cretaceous high latitude climates in Australia. Geochimica et Cosmochimica Acta 63(7/8): 1039-1048.
Dexter, R. W. 1954. An unusual pearl from a freshwater mussel and a pearl-like growth from a crayfish. Ohio Journal of Science 54(4): 241-242.
Dietrich, R. V. 2010. Rock chips: Questions & answers about rocks. Rocks & Minerals 71(6): 412-416.
Dodge, H. W., Jr. 1962. The Geology of Button Bay State Park. Vermont: Department of Forests and Parks.
Elrick, S. D. 2018. Pyrite suns: Unique mineral treasures of Illinois. Geobit 13.
Eskenazi, D. M. 2018. Gogottes: A Rift in Time. London: Eskenazi.
Feliciano, J. M. 1924. The relation of concretions to coal seams. Journal of Geology 32(3): 230-239.
Foster, M. W. 1988. The Illinois Mazon Creek fossils. Rocks & Minerals 63(4): 290-299.
Fritsch, E., and E. B. Misiorowski. 1987. The history and gemology of queen conch “pearls”. Gems & Gemology 23(4): 209-221.
Gardner, J. H. 1908. The physical origin of certain concretions. Journal of Geology 16(5): 452-458.
Gariboldi, K., et al. 2015. The dolomite nodules enclosing fossil marine vertebrates in the East Pisco Basin, Peru: Field and petrographic insights into the Lagerstätte formation. Palaeogeography, Palaeoclimatology, Palaeoecology 438: 81-95.
Garner, K. B. 1936. Concretions near Mount Signal, lower California. American Journal of Science s5-31(184): 301-311.
Garner, P. 1995. Rapid formation of calcium carbonate concretions in a north Norfolk marsh. Origins 18: 13-14. [PDF]
Gewelt, M., and C. Ek. 1988. Les concretions carbonates des grottes: Aperçu synthetique. Annales de la Société Géologique de Belgique 111: 9-19.
Gilman, R. A., and W. J. Metzger. 1967. Cone-in-cone concretions from western New York. Journal of Sedimentary Petrology 37(1): 87-95.
Gratacap, L. P. 1884. Opinions upon clay stones and concretions. American Naturalist 18(9): 882-892.
Gregory, D., et al. 2019. The formation mechanisms of sedimentary pyrite nodules determined by trace element and sulfur isotope microanalysis. Geochimica et Cosmochimica Acta 259: 53-68.
Hainschwang, T., et al. 2010. A cautionary tale about a little-known type of non-nacreous calcareous concretion produced by the Magilus antiquus marine snail. Journal of Gemmology 32(1-4): 15-22.
Hanni, H. A. 1995. A short synopsis of pearls: Natural, cultured, imitation. Journal of the Gemmological Association of Hong Kong 18: 43-46.
Hayes, J. B. 1964. Geodes and concretions from the Mississippian Warsaw Formation, Keokuk Region, Iowa, Illinois, Missouri. Journal of Sedimentary Petrology 34(1): 123-133.
Hesse, R., C. Fong, and D. Schumann. 2019. Origin of spherulitic and cone-in-cone concretions in Cambro-Ordovician black shales, St Lawrence Estuary, Quebec, Canada. Geological Magazine 156: 1793-1804.
Ho, J. W. Y. 2015. Large natural quahog pearl. Gems & Gemology 51(1): 63-64.
Holden, W. F., and E. H. Carlson. 1979. Barite concretions from the Cleveland Shale in north-central Ohio. Ohio Journal of Science 79(5): 227-232.
Hsu, T., A. Lucas, and V. Pardieu. 2015. Splendor in the Outback: A visit to Australia’s opal fields. Gems & Gemology 51(4): 418-427.
Hudson, J. D., et al. 2001. Septarian concretions from the Oxford Clay (Jurassic, England, UK): Involvement of original marine and multiple external pore fluids. Sedimentology 48: 507-531.
Huggett, J. 2016. Puddingstones and related silcretes of the Anglo-Paris Basin – an overview. Proceedings of the Geologists’ Association 127: 297-300.
Huizing, T. E., and R. Peter Richards. 2021. Connoisseur’s choice: Sand calcite, Rattlesnake Butte, South Dakota. Rocks & Minerals 96: 414-431.
Janssen, K., et al. 2022. The complex role of microbial metabolic activity in fossilization. Biological Reviews 97: 449-465.
Jones, B. 2009. Cave pearls—The integrated product of abiogenic and biogenic processes. Journal of Sedimentary Research 79: 689-710.
Jones, F. G., and B. H. Wilkinson. 1978. Structure and growth of lacustrine pisoliths from recent Michigan marl lakes. Journal of Sedimentary Petrology 48(4): 1103-1110.
Jurkowska, A., and E. Świerczewska-Gladysz. 2020. Evolution of Late Cretaceous Si cycling reflected in the formation of siliceous nodules (flints and cherts). Global and Planetary Change 195: 103334.
Kershaw, S., and L. Guo. 2016. Beef and cone-in-cone calcite fibrous cements associated with the end-Permian and end-Triassic mass extinctions: Reassessment of processes of formation. Journal of Palaeogeography 5(1): 28-42.
Kidder, D. L. 1985. Petrology and origin of phosphate nodules from the Midcontinent Pennsylvanian epicontinental sea. Journal of Sedimentary Petrology 55(6): 809-816.
Kindle, E. M. 1923. Range and distribution of certain types of Canadian Pleistocene concretions. Bulletin of the Geological Society of America 34: 609-647, plates 1-12.
Knerr, E. B. 1897-1898. Silico barite nodules from near Salina, Kan. Trans. Kansas Academy of Science 16: 43-44.
Korshunov, V. V., and E. V. Shavrina. 1998. Gypsum speleothems of freezing origin. Journal of Cave and Karst Studies 60(3): 146-150.
Kwiatkowski, S. 2005. Origin of chert nodules from the Polish Muschelkalk, Middle Triassic. Annales Societatis Geologorum Poloniae 75: 287-308.
Lin, C. Y., et al. 2020. The microbially driven formation of siderite in salt marsh sediments. Geobiology 18: 207-224.
Liu, X., et al. 2012. The role of matrix proteins in the control of nacreous layer deposition during pearl formation. Proceedings of the Royal Society B 279: 1000-1007.
Lloyd, S. J., and W. M. Berelson. 2016. The modern record of “concretionary” carbonate: Reassessing a discrepancy between modern sediments and the geologic record. Chemical Geology 420: 77-87.
Locock, A. J., et al. 2020. Fossil, ichnofossil, or concretion: The enigma of “Dinocochlea ingens.” Sedimentary Geology 399: 105619.
London, D. 2008. The barite roses of Oklahoma. The Mineralogical Record 39(July-August): 277-292.
Loope, D. B., and R. M. Kettler. 2015. The footprints of ancient CO2-driven flow systems: Ferrous carbonate concretions below bleached sandstone. Geosphere 11(3): 1-15.
Loope, D. B., and R. M. Kettler. 2019. Rinded iron-oxide concretions in Navajo Sandstone along the trail to Upper Calf Creek Falls, Garfield County. in: Milligan, M., et al. (eds.) Utah Geosites. Utah Geological Association Publication 48.
Loope, D. B., et al. 2012. Rinded iron-oxide concretions: Hallmarks of altered siderite masses of both early and late diagenetic origin. Sedimentology 59: 1769-1781.
Lovell, B. 2015. Hertfordshire puddingstone: relationship to the Paleocene-Eocene Thermal Maximum and a perspective on human-induced climate change. Proceedings of the Geologists’ Association 126: 8-13.
Loyd, S. J., et al. 2014. Clumped-isotope constraints on cement paragenesis in septarian concretions. Journal of Sedimentary Research 84: 1170-1184.
Lugli, S., W. U. Reimold, and C. Koeberl. 2005. Silicified cone-in-cone structures from Erfoud (Morocco): A comparison with impact-generated shatter cones. in: Koeberl, C., and H. Henkel (eds.). Impact Tectonics. Berlin: Springer-Verlag. Pp. 81-110.
Lyle, A., et al., eds. 2008. Kansas Field Conference: Smoky Hill and Republican River Valleys. Kansas Geological Survey Open-File, Report 2008-7.
Maliva, R. G. 1987. Quartz geodes: Early diagenetic silicified anhydrite nodules related to dolomitization. Journal of Sedimentary Petrology 57(6): 1054-1059.
Maliva, R. G., and R. Siever. 1989. Nodular chert formation in carbonate rocks. Journal of Geology 97: 421-433.
Mamay, S. H., and E. L. Yochelson. 1962. Occurrence and significance of marine animal remains in American coal balls. Geological Survey Professional Paper 354-1.
Marshall, J. D., and D. Pirrie. 2013. Carbonate concretions—explained. Geology Today 29(2): 53-62.
Martill, D. M. 1988. Preservation of fish in the Cretaceous Santana Formation of Brazil. Palaeontology 31(Part I): 1-18.
Maxwell, J. A. 1963. Geochemical Study of some Chert and Related Deposits. Geological Survey of Canada, Bulletin 104.
McAllister, D., S. L. Cumbaa, and C. R. Harington. 1981. Pleistocene fishes (Coregonus, Osmerus, Microgadus, Gasterosteus) from Green Creek, Ontario, Canada. Canadian Journal of Earth Sciences 18(8): 1356-1364.
McConnell, D. 1935. Spherulitic concretions of dahllite from Ishawooa, Wyoming. American Mineralogist 20(10): 693-698.
McCoy, V. 2014. Concretions as agents of soft-tissue preservation: A review. in: Laflamme, M., et al. (eds.) Reading and Writing of the Fossil Record: Preservational Pathways to Exceptional Fossilization. The Paleontological Society Papers, Vol. 20. Pp. 147-161.
McCoy, V., R. T. Young, and D. E.G. Briggs. 2015. Factors controlling exceptional preservation in concretions. Palaios 30: 272-280.
McCoy, V. E., et al. 2020. Chemical signatures of soft tissues distinguish between vertebrates and invertebrates from the Carboniferous Mazon Creek Lagerstätte of Illinois. Geobiology 18: 560-565.
McLaughlin, D., and R. Grant. 2012. Azurite suns from the Malbunka Copper Mine Northern Territory Australia. Rocks & Minerals 87(6): 490-501.
McMahon, S., A. Van Smeerdijk Hood, and D. McIlroy. 2017. The origin and occurrence of subaqueous sedimentary cracks. In: Brasier, A. T., et al. (eds.) Earth System Evolution and Early Life: A Celebration of the Work of Martin Brasier. Geological Society, London, Special Publications 448: 285-309.
Meinhold, G., et al. 2019. First record of carbonates with spherulites and cone-in-cone structures from the Precambrian of Arctic Norway, and their palaeoenvironmental significance. Precambrian Research 328: 99-110.
Melim, L. A., and M. N. Spilde. 2018. A new unified model for cave pearls: Insights from cave pearls in Carlsbad Cavern, New Mexico, U.S.A. Journal of Sedimentary Research 88: 344-364.
Milnes, A. R., Thiry, M., and B. B. Mohammed. 2015. Pleistocene cold climate groundwater silicification, Jbel Ghassoul region, Missour Basin, Morocco. Journal of the Geological Society 172: 125-137.
Mitchell, R. S. 1970. Barite and lepidocrocite in spherulitic dahllite from Big Horn Basin, Wyoming. Rocks & Minerals 45(2): 90-92.
Mitchell, R. S., and W. C. Sherwood. 1958. Dahllite pseudomorphs after pyrite concretions from Big Horn Basin, Wyoming. American Mineralogist 43(May-June): 600-603.
Mojarro, A., et al. 2022. Comparative soft-tissue preservation in Holocene-age capelin concretions. Geobiology 20(3): 377-398.
Monroe, J. S., and R. V. Dietrich. 1990. Pseudofossils. Rocks & Minerals 65(March-April): 150-158.
Morris, R. W. 2010. Fossiliferous cherts of the Midwest: Their origin, composition, and prehistoric use. Ohio Archaeologist 60(1): 25-31.
Mougenot, D. 2000. Sand roses of Saudi Arabia. https://brcgranier.pagesperso-orange.fr/gmeop/Mougenot.html
Mozley, P. S. 1995. Concretions, bombs, and ground water. Lite Geology (New Mexico Bureau of Mines and Mineral Resources) (Winter): 1-3.
Müller, K. J. 1985. Exceptional preservation in calcareous nodules. Philosophical Transactions of the Royal Society, London B 311: 67-73.
Muramiya, Y., et al. 2020. Rapid formation of gigantic spherical dolomite concretion in marine sediments. Sedimentary Geology 404: 105664.
Muramiya, Y., et al. 2022. Glendonite concretion formation due to dead organism decomposition. Sedimentary Geology 429: 106075.
Neutkens, H., Löffler, I., and W. E. Wilson. 2014. Sand calcite from Fontainebleau, France. The Mineralogical Record 45(July-August): 439-451.
Pacyna, G., and D. Zdebska. 2012. Carboniferous plants preserved within sideritic nodules—a remarkable state of preservation providing a wealth of information. Acta Palaeobotanica 52(2): 247-269.
Papp, R., et al. 2012. Desert roses – A crystal morphological study. Acta Mineralogica-Petrographica, Abstract Series, Szeged 7: 101.
Pardieu, V. 2009. Concise field report: Volume 2 ‐ part 1, Melos and their Pearls in Vietnam (May‐June). Field Reports http://www.giathai.net/lab.php
Parry, L. A., et al. 2018. Soft-bodied fossils are not simply rotten carcasses—Toward a holistic understanding of exceptional fossil preservation. BioEssays 40: 1700167.
Parry, W. T. 2011. Composition, nucleation, and growth of iron oxide concretions. Sedimentary Geology 233: 53-68.
Perry, R. S., and M. A. Sephton. 2008. Solving the mystery of desert varnish with microscopy. InFocus 11(Sept.): 62-76.
Potter, S. L., et al. 2011. Characterization of Navajo Sandstone concretions: Mars comparison and criteria for distinguishing diagenetic origins. Earth and Planetary Science Letters 301: 444-456.
Potter-McIntyre, S. L., M. A. Chan, and B. J. McPherson. 2014. Concretion formation in volcaniclastic host rocks: Evaluating the role of organics, mineralogy, and geochemistry on early diagenesis. Journal of Sedimentary Research 84: 875-892.
Pratt, B. R. 2001. Septarian concretions: Internal cracking caused by synsedimentary earthquakes. Sedimentology 48: 189-213.
Prest, V. K. 1990. Laurentide ice-flow patterns: A historical review, and implications of the dispersal of Belcher Islands erratics. Géographie Physique et Quaternaire 44(2): 113-136.
Prest, V. K., J. A. Donaldson, and H. D. Mooers. 2000. The omar story: The role of omars in assessing glacial history of west-central North America. Géographie Physique et Quaternaire 54(3): 257-270.
Reitner, J., et al. 2005. Concretionary methane-seep carbonates and associated microbial communities in Black Sea sediments. Palaeogeography, Palaeoclimatology, Palaeoecology 227: 18-30.
Roberge, J., and D. Caron. 1983. The occurrence of an unusual type of pisolite: The cubic cave pearls of Castleguard Cave, Columbia Icefields, Alberta, Canada. Arctic and Alpine Research 15(4): 517-522.
Sargent, K. A., and H. D. Zeller. 1984. Sand-calcite crystals from Garfield County, Utah. U.S. Geological Survey Bulletin 1606. Alexandria, VA: U.S. Geological Survey.
Sass, S. 2000. St. Augustine coquina: History and quarrying techniques. The Conservation and Preservation of Coquina. Tallahassee, FL: Bureau of Historic Preservation. pp. 35-42.
Scarratt, K., and H. Hanni. 2004. Pearls from the lion’s paw scallop. Journal of Gemmology 29(4): 193-203.
Schwimmer, D. R., and W. M. Montante. 2007. Exceptional fossil preservation in the Conasauga Formation, Cambrian, northwestern Georgia, USA. Palaios 22: 360-372.
Seilacher, A. 2001. Concretion morphologies reflecting diagenetic and epigenetic pathways. Sedimentary Geology 143: 41-57.
Self, C. A. 2004. The internal organization of speleothems. Acta Carsologica 33/1(16): 245-255.
Self, C. A., and C. A. Hill. 2003. How speleothems grow: An introduction to the ontogeny of cave minerals. Journal of Cave and Karst Studies 65(2): 130-151.
Selleck, B. W., P. F. Carr, and B. G. Jones. 2007. A review and synthesis of glendonites (pseudomorphs after ikaite) with new data: Assessing applicability as recorders of ancient coldwater conditions. Journal of Sedimentary Research 77: 980-991.
Sellés-Martinez, J. 1994. New insights in the origin of cone-in-cone structures. Carbonates and Evaporites 9(2): 172-186.
Sellés-Martínez, J. 1996. Concretion morphology, classification and genesis. Earth-Science Reviews 41: 177-210.
Shahid, S. A., and M. A. Abdelfattah. 2009. Gypsum polymorphism in the desert environment of Abu Dhabi Emirate. European Journal of Scientific Research 29(2): 237-248.
Sheldon, J. M. A. 1900. Concretions from the Champlain Clays of the Connecticut Valley. Boston: Sheldon.
Siemers, W. A., T. M. Stanley, and N. H. Suneson. 2000. Geology of Arcadia Lake Parks—An introduction and field-trip guide. Oklahoma Geology Notes 60(1): 4-17.
Smelror, M., and D. Knaust. 2021. Trace fossils and palynomorphs in Holocene calcareous concretions from Lake Selbusjøen, Mid-Norway: Post-glacial environmental records. The Holocene 31(5): 732-745.
Smith, J. R. 2007. Geodes and geodes after fossils from Heltonville Lawrence County Indiana. Rocks & Minerals 82(3): 200-208.
Soleilhavoup, François. 2011. Microformes d’accumulation et d’ablation sur les surfaces désertiques du Sahara. Géomorphologie 17(2): 173-186.
Sturman, N., et al. 2014. Observations on pearls reportedly from the Pinnidae family (pen pearls). Gems & Gemology 50(3): 202-215.
Tanner, L. H. 1996. Armoured mud balls revisited. Atlantic Geology 32: 123-125.
Tarr, W. A. 1933. The origin of the sand barites of the Lower Permian of Oklahoma. American Mineralogist 18(6): 260-272.
Taylor, P. D., and C. Sendino. 2011. A new hypothesis for the origin of the supposed giant snail Dinocochlea from the Wealden of Sussex, England. Proceedings of the Geologists’ Association 122: 492-500.
Thiry, M., and B. Maréchal. 2001. Development of tightly cemented sandstone lenses in uncemented sand: example of the Fontainebleau sand (Oligocene) in the Paris Basin. Journal of Sedimentary Research 71(3): 473-483.
Thiry, M., et al. 2020. Sand calcites as key to Pleistocene periglacial landscapes. Quaternary Research 1-20. doi.org/10.1017/qua.2020.98
Tilden, P. M. 1954. Donax the builder. Rocks & Minerals 29: 11-12.
Tirmizi, N. M., and Q. B. Kazmi. 1990. Note on a pearl-like object from a shrimp, Penaeus indicus H. Milne Edwards (Decapoda, Natantia). Copeia 59(3): 307-309.
Tredici, S. M., et al. 2018. Calcite-forming Bacillus licheniformis thriving on underwater speleothems of a hydrothermal cave. Geomicrobiology Journal 35(9): 804-817.
Tripp, M., et al. 2022. Fossil biomarkers and biosignatures preserved in coprolites reveal carnivorous diets in the Carboniferous Mazon Creek ecosystem. Biology 11(1289): 1-22.
Van Tuyl, F. M. 1916. The geodes of the Keokuk beds. American Journal of Science 42(1): 34-42.
Vasileva, K., et al. 2020. Multi-proxy study of cannon-ball concretions with glendonites from Paleogene-Neogene sediments of Sakhalin Island: Implication for concretion growth and ikaite-calcite trans-formation. EGU General Assembly 2020. EGU2020-4041.
Vickers, M., et al. 2018. An improved model for the ikaite-glendonite transformation: Evidence from the Lower Cretaceous of Spitsbergen, Svalbard. Norwegian Journal of Geology 98: 1-15.
Wetzel, A., and M. Bojanowski. 2022. Radish concretions grown in mud during compaction. Sedimentology 69: 750-774.
White, J. S. 2003. Let’s get it right: Selenite die, you accursed term! Rocks & Minerals 78(6): 420-421.
Wise, R. W. 1993. Queensland boulder opal. Gems & Gemology 29(1): 4-15.
Woodward, B. B. 1922. On Dinocochlea ingens, n. gen. et sp., a gigantic gastropod from the Wealden Beds near Hastings. Geological Magazine 59(6): 242-247.
Worsley, P. 2019. Geology of the Clatford Bottom catchment and its sarsen stones on the Marlborough Downs. Mercian Geologist 19(4): 242-252.
Yoshida, H., et al. 2018. Fe-oxide concretions formed by interacting carbonate and acidic waters on Earth and Mars. Science Advances 4: eaau0872.
Yoshida, H., et al. 2021. Syngenetic rapid growth of ellipsoidal silica concretions with bitumen cores. Scientific Reports 11: 4230.
Young, R. B. 1914. Note on pyritic concretions in Karoo sandstones. South African Journal of Geology 17(1): 55-56.
Zatoń, M. 2010. Feature: Hiatus concretions. Geology Today 26(5): 186-189.
