https://bereket-haileab.geology.sites.carleton.edu/files/original/5ffd37027eb21e1d3f513cfdc97b7ce2.jpg 42f61b96377a08198104623a971a1129 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Igneous Rocks Subject The topic of the resource This collection covers both volcanic and intrusive rocks, including rhyolites, granites, diorites, andesites, basalts, gabbros, diabases, pumices, obsidians, syenites, phonolites, peridotites, carbonatites, dacites, trachyte, dunites, xenoliths, ignimbrites, and pegmatites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Thin section and hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-87b Subject The topic of the resource Komatiite Description An account of the resource Major Minerals: olivine (forsteritic composition) Minor Minerals: serpentine, iron oxides (magnetite) Textures: spinifex texture, spinifex olivine, sheaf-like olivine aggregates, acicular olivine phenocrysts, olivine pseudomorphs Alteration: extensive serpentinization of olivine and oxidation to magnetite BH250-87b is a komatiite specimen from Australia, likely derived from one of the classic Archean greenstone belts of Western Australia, where some of the world’s best-preserved komatiitic sequences occur. Australian komatiites are globally significant because they preserve exceptionally well-developed spinifex textures and are closely associated with economically important nickel sulfide deposits. This sample was collected in Australia and generously donated to the BH250 Collection by John Goodge, Class of 1980. This specimen expands the geographic scope of the BH250 komatiite suite and allows direct comparison between Canadian and Australian Archean ultramafic volcanic systems. Although both formed from extremely hot magnesium-rich magmas, differences in metamorphic history, deformation, weathering, and alteration can produce noticeable differences in hand sample appearance and thin-section textures. BH250-87b displays classic bladed to acicular olivine spinifex textures with strong alteration to serpentine and iron oxides. The specimen demonstrates how original olivine crystal morphology can remain remarkably preserved even after extensive metamorphism and hydrothermal replacement. In some areas, radiating sheaf-like aggregates of olivine pseudomorphs create dramatic fan-shaped patterns characteristic of spinifex-textured komatiites. The Australian specimen is particularly valuable for teaching because it highlights the global distribution of Archean komatiitic volcanism and reinforces the interpretation that hotter mantle conditions were widespread during the Archean Eon. When examined alongside the Munro Township samples, students can compare mineralogy, crystal habit, alteration textures, and preservation styles between different Archean terranes. Comparative Importance of the Komatiite Suite Together, BH250-87, BH250-161, and BH250-87b form one of the strongest teaching groups within the BH250 Collection for illustrating: • Archean mantle temperatures and early Earth volcanism • Ultramafic lava compositions and high-Mg magmas • Formation of spinifex textures through rapid crystal growth • Olivine crystallization and skeletal crystal morphology • Serpentinization and hydrothermal alteration of ultramafic rocks • Greenstone belt geology and Archean tectonic environments • Economic associations with nickel sulfide mineralization • Variations in preservation between different Archean terranes These specimens collectively provide students with a rare opportunity to study true komatiites from two classic Archean localities and to directly observe textures that record some of the hottest volcanic eruptions in Earth history. Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample BH250-87b. Housed at Carleton College in Minnesota. Contributor An entity responsible for making contributions to the resource Bereket Haileab John Goodge '80 Type The nature or genre of the resource Thin section and hand sample Relation A related resource <iframe width="100%" height="600" style="border: 0;" src="https://carleton.maps.arcgis.com/apps/instant/media/index.html?appid=54e42610d4bf414fadae93f57ac0bbce" frameborder="0" allowfullscreen="allowfullscreen">iFrames are not supported on this page.</iframe><br />View on ArcGIS Online <a href="https://carleton.maps.arcgis.com/home/item.html?id=54e42610d4bf414fadae93f57ac0bbce">here</a><br /><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1eKdXSM7jibrbEpAS4tZzgZptyvG_BJdW/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1VoRJifo9iocqi39SJNaiL3Nos3TW3Kec/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1qdYLskf4NiC8z9s47V7Whjg4GZ2MLdx-/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1-5dB-Fyd-hbTGz3-zK4KVHsnJnCpp9uH/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1uM8OUUF_nQvpNI2qZEZ7QBj8Ublh8cPS/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1ADjk29c3MthohW1VDeDpWbVmQopc_T_6/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1OitwXrA5o7ve2nc3wpur06oWj80ZPNI1/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1PCfD0w2gANewHT99gDdPCk4o1L_89V94/preview" allow="autoplay"></iframe> Creator An entity primarily responsible for making the resource Bereket Haileab John Goodge '80 Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Australia, collected by John Goodge '80 Ancient mantle melting Archean greenstone belt Archean volcanism Australia komatiite sample Early Earth mantle Forsteritic olivine High-temperature lava Iddingsite igneous komatiite Magnesium-rich lava Magnetite olivine Olivine alteration Olivine to iddingsite Olivine to magnetite Olivine to serpentine Serpentine spinifex Spinifex texture ultramafic Ultramafic Volcanic Rock volcanic