https://bereket-haileab.geology.sites.carleton.edu/files/original/351795e8c926a8b3fd45c2f791315c72.jpg d02b87f55abb17b5469ef0335e9c121e 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 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 BH250-168 Subject The topic of the resource Amigdolodial Basalt Description An account of the resource Major Minerals: clinopyroxene, plagioclase Minor Minerals: zeolite, quartz DescriptionMajor Minerals: clinopyroxene, plagioclase, glass Minor (secondary) minerals (vesicle fills): epidote , chlorite, quartz, zeolite Texture: amygdaloidal basalt (vesicles filled with secondary minerals) Amygdules and amygdaloidal basalt: Vesicles in basalt filled with concentrically zoned secondary minerals are a striking result of post-eruption processes, recording interactions between fluids and solidified rock. Vesicles form when volatiles (e.g., H₂O, CO₂, SO₂) escape from magma during eruption. As lava cools rapidly, gas bubbles become trapped, leaving spherical or elongated cavities. After solidification, hydrothermal fluids or groundwater enter the basalt and deposit minerals inside the vesicles — a process known as amygdaloid formation. The infilled vesicles, called amygdules, contain secondary minerals. Amygdules are rounded, almond-shaped mineral deposits. These minerals often form concentric bands due to stepwise precipitation as fluid conditions change (e.g., temperature, pH, or chemistry). Early minerals coat the walls; later ones fill the center. Supersaturation of minerals like calcite or zeolites leads to layered deposition. Typical textures include: • Concentric banding – Alternating mineral layers • Botryoidal texture – Grape-like mineral masses • Zonation – Color or compositional variation from rim to core These features not only stand out visually but also reflect the history of fluid-rock interaction and may indicate low-grade metamorphism or hydrothermal alteration. Common secondary minerals include zeolites (see Mara MacDonell '17 comps), analcime, calcite, chlorite, and quartz, each marking shifts in post-volcanic conditions. Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: Minnesota, USA Nearby Geographic Feature: North Shore of Lake Superior GPS Coordinates: 47° 8'41.91"N, 91°28'6.15"W Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample BH250-168. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section Relation A related resource <iframe width="100%" height="600" style="border: 0;" src="https://carleton.maps.arcgis.com/apps/instant/media/index.html?appid=9252ebd931f347daa24b35e8aa963c55" 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=9252ebd931f347daa24b35e8aa963c55">here</a><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1UAFBKpOcvoy7YrqyBGjtRnwNXkyq6WLg/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1CujEyQERyllJUbhf1R30Ja_ldcimbxrZ/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1rlV5CRAQWuWasU9HeATB2WWQMt9uAwEw/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1eVTrrjybUnjvLqCJ8DS123CVUAE-SHU8/preview" allow="autoplay"></iframe> Creator An entity primarily responsible for making the resource Bereket Haileab basalt igneous mafic volcanic