Hugo van Schrojenstein Lantman
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Hugo van Schrojenstein Lantman
@hugolantman.bsky.social
800 followers 470 following 92 posts
Geology Postdoc at Utrecht University
Mechanical behaviour of minerals using nanoindentation

Fan of microstructures, petrology, metamorphism, fluids, subduction, earthquakes, stress and strain.
Occasionally takes pictures of rocks.
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Some bonus #kyanite pictures #MinCup25
A single crystal of blue kyanite. This crystal contains kinks, visible as lines within the crystal, and are the result of deformation. Some white quartz matrix is visible in the background. Two blades of blue kyanite in a garnet-phengite-quartz rock. The phengite is visible as silvery shimmering patches, the graphite is greyish, and the few garnet are small red-brown roundish crystals mostly in the left of the specimen. A blue-white kyanite-quartz lens in an outcrop of gray graphitic schist. A camera case in the bottom of the image provides a rough scale. Close-up of a white-gray schist outcrop containing abundant garnet (orange circular crystals), a few blue kyanite crystals, and plenty of white quartz and silvery mica. The metal spike in the left of the image is the tip of a rock hammer.
October 1, 2025 at 12:01 PM
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Since kyanite made it to the final of Mineral Cup, I decided to contribute. Vote kyanite!

Not only is kyanite gorgeous, it's also a key metamorphic index mineral and thus one of my favourite minerals to find. Here are a few examples I've come across.

See alt text for details

#MinCup25 #kyanite
A single crystal of blue kyanite on a matrix of white quartz. From the Betic Cordillera, Spain A green-blue kyanite eclogite with a reddish vein of garnet, bordered by more dark blue kyanite. From Pohorje, Slovenia. 2 euro cent coin for scale. Bright blue specks of kyanite in a gray-white matrix. These rocks are originally granulite of the Baltica basement, locally transformed to eclogite. From Holsnøy, Norway One of the most confusing samples I have ever found, this rock consists entirely of white kyanite, muscovite and quartz - here pictured on top of a red notebook with a mechanical pencil as scale. The orange colour seems to be iron oxide from the surroundings. Before finding this, I did not know that kyanite could be white! From the Betic Cordillera, Spain.
October 1, 2025 at 11:44 AM
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Bit of an unusual #ThinSectionThursday
Over the past weeks, I've been busy collecting data with the Triboindenter, performing deformation experiments on grains in thin sections. See below a topography 3D model of one of these indents (looks like a crater), also collected with the indenter.
A three-dimenisonal graph showing a yellowish surface, representing the topography of a mineral grain. In the center is a crater-like feature, an indent that is the result of a nanoindentation experiment. The topography map is 15 micrometers by 15 micrometers, and the topography is in the order of 10s to ~100 nanometers.
May 1, 2025 at 3:01 PM
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Same here from the Netherlands last night
February 1, 2025 at 4:33 PM
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Also metamorphic rocks can have really cool Fe-Ti oxides! I found this cluster with intergrowths of Ti-magnetite and Mn-ilmenite (white & grey lines resp.), and rutile with non-Mn-ilmenite exsolution (grey & white lines resp.), in garnetite from Lago di Cignana.
A grayscale image taken with the backscattered electron detector of a scanning electron microscope. The image consists of various blobs of dark and bright grays with occasionally lines and dots throughout the blobs. Each brightness level corresponds to a mineral, in this case Fe-Ti-oxides and garnet. On the left-hand side is a large bright grain of Ti-magnetite with irregular lines of intermediate gray, Mn-ilmenite. On the right-hand side is a darker gray grain with white speckles and a few straight white lines, this is a grain of rutile with ilmenite inside. A zoomed-out version of the previous image; there is more dark grey (garnet) surrounding the Fe-Ti-oxides
December 19, 2024 at 8:41 AM
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Today is my first day as postdoc at Utrecht University! For the next three years, I will be focusing on the mechanical behaviour of minerals in various settings using nanoindentation, as part of EPOS-eNLarge and working with Dr Alissa Kotowski. Excited to get started!
December 2, 2024 at 10:53 AM
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These structures consist of mostly metamorphic and igneous megaliths, unlike the local bedrock. Rather, these rocks come from Scandinavia, moved by ice during the Saale Glaciation. We can see various interesting features: large crystals, dikes, deformation structures, and quartz veins.
A closeup of one of the glacial erratics within Hunebed D50. The rock is partially covered in moss and lichens, but some large pink crystals of K-feldspar stand out, indicating that this is an igneous rock. Index finger for scale. A glacial erratic hosting a dike. A brownish rock with a darker, fine-grained irregularly shaped area inside; this area is where magma intruded and solidified as a dike. Hand for scale. A rock with a slight fabric to it - subhorizontal lines formed by the arrangement of minerals. In the middle of the picture is a patch of grey with some orange, this is a quartz vein with some iron oxide. Index finger for scale. Apologies for slightly unfocused picture. This rock is a so-called Augengneiss; large crystals are surrounded by a fine-grained matrix. it is igneous in origin and has been deformed subsequently. In the bottom right of the image we can see vertical to subvertical stripes formed by the elongation and arrangement of minerals. The hand is pointing at a plane on which we see some lighter crystals surrounded by darker material. Apologies for slightly unfocused picture.
November 27, 2024 at 10:57 AM
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Today: geology meets archaeology! This is what we call a "hunebed" in Dutch: a neolithic burial structure built by people of the Funnelbeaker culture between ~3400-3000 BC. Many are found across the northern Netherlands and parts of Germany and Denmark. But what are they made of?
Hunebed D50, a neolithic burial structure in a grassy field surrounded by trees, near the Dutch town of Noord-Sleen. An inner ring of half buried large rocks is covered by horizontal flat rocks. This structure is surrounded by a second ring of half-buried rocks. Initially these rocks would have been covered by a mound of soil. Many hunebedden were built east-west with the entrance facing south. Hunebed D50, the same one as the previous picture, within the outer ring of half buried rocks. We see five half-buried rocks in the foreground, all covered by flat horizontal rocks that are also supported by more half-buried rocks in the back, out of view. Behind these rocks are trees.
November 27, 2024 at 10:54 AM
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Today my time in Norway sadly comes to an end. It has been an incredible time and I'm deeply grateful to all my friends and coworkers at The Njord Centre.

Soon: the start of my next adventure, and papers about my work at the university of Oslo!
A large red brick building: the Physics building of the University of Oslo, where the Njord Centre is housed
November 17, 2024 at 3:54 PM
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Felt like sharing a picture of one of my favourite rocks. It's a vein of quartz, kyanite, and phengite, hosted in a matrix of graphitic garnet schist.
A light-coloured rock on a black desk, with a red Swiss army knife for scale. The main part of the rock is white-ish with blue bladed crystals, and the outer part of the rock (especially bottom and right) is more grey-ish from the graphite.
November 5, 2024 at 12:51 PM
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It's the season for gorgeous sunsets. Wavy orange clouds over Oslo and the fjord, seen from the physics building of the university of Oslo
A light blue sky below dark clouds with orange streaks
October 22, 2024 at 4:08 PM
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It's the Mineral Cup final and kyanite needs your vote! This blue mineral is visually stunning and really interesting from a scientific point of view. #MinCup24 #Kyanite
A deep blue crystal of kyanite
October 1, 2024 at 9:15 AM
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I've been quietly participating in Mineral Cup so far but now that corundum is in danger, it's time to bring out the big guns. See here, the most beautiful rock on earth. With corundum. Unfortunately I do not know the source of the picture or the rock. Vote corundum!
A large gray rock with elongated gem-quality crystals of blue sapphire (corundum). It is the most beautiful rock ever.
September 18, 2024 at 7:05 PM
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Haha thank you! Meanwhile this is the best I can do when it comes to northern lights
A grainy black imagine with a barely noticeable dark green horizontal band of northern lights
September 15, 2024 at 4:51 PM
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And here as seen from Ullerntoppen!
A sunset in an orange-blue sky over a dark backdrop of hills
September 7, 2024 at 6:09 PM
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Was leafing through some old pictures and feeling the need to share this one - it's a small outcrop from Southern Spain, basaltic-gabbroic rocks that have been metamorphosed. You can see the strong effect that the composition and texture of the initial rock has on the metamorphic product.
A small outcropping of rock with a rock hammer on top of it. The rock consists of three parts, a fine-grained grey rock (amphibolite) on the left, a speckled amphibolite on the right with large plagioclase and epidote grains, and a dark middle part containing large red garnets.
September 7, 2024 at 12:26 PM
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Having a great time in the Bergen Arcs with these absolute petrological and structural wonders
August 15, 2024 at 1:32 PM
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Bluesky needs some more cool geo images, so here's some orthopyroxene from a serpentinized peridotite (Semail ophiolite, Oman), seen with cross-polarised light in the optical microscope. The coloured patches seem to be exsolution features.
May 28, 2024 at 9:54 AM
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A beautifully exposed normal fault, featuring prof Luca Menegon pointing at the latest active fault plane
May 11, 2024 at 10:55 AM
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How is Norway so gorgeous?
May 10, 2024 at 4:23 PM
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It's an eclogite kind of day
May 8, 2024 at 4:47 PM
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Shear sense indicators doing their thing
May 7, 2024 at 5:39 PM
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Time for the Tectonics field trip with UiO to the western Gneiss region. Day 1:migmatite, flame structures, tillite and an excellent view
May 6, 2024 at 4:46 PM
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One of my favourite office rocks: a "fossil" earthquake! Pseudotachylyte (dark glassy veins formed from quenching of a frictional melt) with clasts, in a monzonite from Northern Norway.
A brown-grey rock (Monzonite) that is crosscut by very dark lines in a chaotic distribution. These dark lines are pseudotachylyte, and locally contain small pieces of the brown host rock. A brown-grey rock (Monzonite) that is crosscut by very dark lines in a chaotic distribution. These dark lines are pseudotachylyte, and locally contain small pieces of the brown host rock.
February 7, 2024 at 9:32 AM
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Nature just treated Oslo to some stunning nacreous / polar stratospheric clouds!
Pink-pearlescent clouds high in a deep blue to orange-yellow sunset sky Pearlescent clouds high in a deep blue to yellow sunset sky
December 19, 2023 at 3:32 PM