______October 2014 Mineral N e w s ------low. salinity high and current circulation low just prior to ikaite precipation. Such evidence is consistent with the previous Glendonites from the hypotheses of their formation. England (1976) summarized the theory that within a highly saline and cold water environment Arctic Wildlife Refugee, (such as the arctic would have had in the Early Tertiary) mirabilite and ikaite could have directly precipitated on the sea floor muds. The alteration of ikaite to would have occurred soon North Slope, Alaska afterw ards, before lithification of the muds. Mark Ivan Jacobson Denver, CO

The arctic coastal plain is a treeless, almost barren, rolling grassland. This is an environment where Musk Oxen and Caribou are the populous inhabitants. Within this environment, near the shores of the Beaufort Sea are found glendonites, calcite pseudomorphs after ikaite (CaC03 • 6H:0).The Danish mineralogist, Hans Pauly (Pauly 1963). first described the mineral from an occurrence in the inner Ika Fjord, south , close to Ivigtut. the first locality of . Thereafter, these pseudomorphs were reported from several localities in Australia. These cold-temperature formed ikaite pseudomorphs received their name from the locality at Glendonbrook, New South Wales, Australia. Figure 2. An elongated glendonite with smaller subsidiary from the banks of Carter Creek, National Arctic Wildlife Refugee. Collected circa 1970. The occurrence of glendonite. which were considered oddities by early North Slope Alaska geologists, were discovered erica 1965 Since their work was aimed towards an understanding of the biostratigraphy and lithology of the Tertiary , the occurrence of glendonites did not merit further attention. These crystals and their occurrence were brought to my attention by senior Chevron geologists in 1978, prior to and after my field work along Carter Creek. Alaska.

References England, Brian M. 1976. Glendonites, their origins and description. Mineralogical Record, v. 7:2, p. 60-68. Pauly, Hans. 1963. Ikait, Nyt mineral der danner skaer. Naturens Figure 1. A pineapple-like glendonite from the banks of Carter Creek, Verden. June. p. 168-192. (in Danish: Ikaite, A new bladed National Arctic Wildlife Refugee. Collected circa 1970. mineral. Nature’s World) The glendonites occur with Early Tertiary (Probably Eocene-Oligocene) aged marine shales. They were found weathering out of the shales along the stream banks of Carter L R Ream Publishing Creek (1002 area) within the National Arctic Wildlife Refugee. MinDex 2011-12 Final Edition Clusters of ikaite pseudomorphs up to two feet in length are Mineral Periodical - Locality Index present at the outcrop. Some of the specimens are similar in Complete through December 2012 with appearance to the pineapple-shaped clusters from New all your mineral periodicals indexed. South Wales, Australia (England 1976). Doubly terminated single Mineral Books and Software at: www.LRReam.com crystals occur up to six inches in length. All the ikaite cry stals have been replaced by massive, fine grained gray-yellow calcite. Occasionally small selenite (gypsum) crystals have formed coatings on the pseudomorphs. PERFECT BOUND ANNUAL EDITIONS The cry stals formed ih a unique geologic environment. Just of Mineral News for 2004-2013 below the stratigraphic interval where the glendonites occur is a $35 per year postpaid! 300 foot interval of paper-thin laminated siliceous marine shales. The siliceous shale is composed of the tests of one-celled siliceous Mineral News animals (nanoplankton floating forms) such as silicioflagellates, 1885 Seminole Trail - Suite 202 diatoms, ebridiants and archaeomonads. The absence of one-celled Charlottesville, VA 22901-1160 calcite fossils indicates that the water depth was below the calcite compensation depth (the depth below which all calcite is dissolved in sea water). This evidence indicates the probable existence of a silled marine basin, where the oxygen content in the water was