Accueil Geo Lab Roches, minéraux et fossiles
Read Oman’s rocks like a geologist Filter by type, search, and open any specimen to learn how it formed, where it occurs in Oman and where to see it on our tours.
Relecture scientifique en cours Le Geo Lab est ouvert en avant-première. Ses explications sont rédigées à partir des sources publiées citées pour chaque élément et sont en cours de vérification par un géologue qualifié ; d’ici là, chaque élément porte la mention Brouillon · en attente de validation par un géologue . Les illustrations et les modèles sont signalés comme tels et ne sont pas des photographies de terrain. Les positions sur la carte sont des zones approximatives.
Les explications scientifiques détaillées du Geo Lab sont encore en anglais. Elles seront traduites une fois validées par notre géologue.
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Scientific illustration · photo needed Magmatiques Péridotite Dense, dark green rock that often weathers to a rusty brown surface. Draft Photo · Oman Magmatiques Gabbro Coarse-grained, speckled dark and light crystals. Draft Scientific illustration · photo needed Magmatiques Dolérite (complexe filonien) Medium-grained dark rock in parallel vertical sheets. Draft Photo · Oman Magmatiques Basalte et laves en coussins Fine-grained dark rock forming rounded, pillow-shaped bodies. Draft Scientific illustration · photo needed Sédimentaires Calcaire Pale grey to cream rock, often containing fossils. Draft Scientific illustration · photo needed Fossil Corail fossile Honeycomb or branching patterns preserved in limestone. Draft Scientific illustration · photo needed Fossil Stromatolite Fine wavy or domed layers in carbonate rock. Draft Scientific illustration · photo needed Sédimentaires Dépôt glaciaire Pebbles and boulders of mixed sizes in a fine-grained matrix. Draft Scientific illustration · photo needed Métamorphiques Éclogite Green rock studded with red garnet crystals. Draft Scientific illustration · photo needed Métamorphiques Roches métamorphiques (schiste) Rocks with a layered, often shiny foliation. Draft Scientific illustration · photo needed Sédimentaires Travertin Pale, porous or banded carbonate rock. Draft
Squeezed Squeezed Hinge: where the beds bend most sharply Anticline: beds fold upward into an arch Limb: the sloping side Syncline: beds fold down into a trough Thin alternating beds make the folds easy to see LEGEND · NOT TO SCALE Light bed Darker bed FOLDED STRATA · CONCEPT SKETCH Scientific illustration · photo needed Structure Pli en fourreau A tube- or cone-shaped fold in strongly deformed rock. Draft Scientific illustration · photo needed Mineral Olivine Olive-green glassy grains. Draft Scientific illustration · photo needed Mineral Grenat Deep red, rounded crystals. Draft Scientific illustration · photo needed Mineral Calcite White to colourless mineral, the main component of limestone and travertine. Draft × Magmatiques
Péridotite Dense, dark green rock Rusty-brown weathered patches Péridotite about 5 cm (illustrative) HAND SPECIMEN · SCIENTIFIC ILLUSTRATION Illustration scientifique of a typical peridotite hand specimen, with the features that identify it — not a photograph. An approved specimen photograph is still needed.
How to recognise it Dense, dark green rock that often weathers to a rusty brown surface.
How it formed Formed in Earth’s upper mantle, below the oceanic crust.
In Oman Forms the mantle section of the Samail ophiolite in the Oman Mountains.
Why it matters A rare chance to walk on rock from the mantle. Its reaction with water and CO₂ is studied for natural carbon capture.
Key minerals Olivine · Pyroxene · Serpentine (alteration) Magmatiques
Gabbro Photo · Oman ⤢ Layered gabbro — Al Batinah Region, Oman Anita Di Chiara · CC BY 3.0 Identifications and locations are as stated by each source and are pending confirmation by our geologist.
How to recognise it Coarse-grained, speckled dark and light crystals.
How it formed Magma that cooled slowly deep in the oceanic crust.
In Oman The lower crust of the Samail ophiolite; zircon in these gabbros is dated to about 96–95 million years ago.
Why it matters Its precise ages tell us when this piece of ocean floor was born.
Key minerals Plagioclase · Pyroxene Magmatiques
Dolérite (complexe filonien) Medium-sized grey crystals Parallel sheet margins Dolérite (complexe filonien) about 5 cm (illustrative) HAND SPECIMEN · SCIENTIFIC ILLUSTRATION Illustration scientifique of a typical dolerite (sheeted dykes) hand specimen, with the features that identify it — not a photograph. An approved specimen photograph is still needed.
How to recognise it Medium-grained dark rock in parallel vertical sheets.
How it formed Magma that filled cracks as the sea floor pulled apart, feeding the lavas above.
In Oman The sheeted dyke complex of the Samail ophiolite.
Why it matters Shows how oceanic crust grows at spreading ridges. Magmatiques
Basalte et laves en coussins Photo · Oman ⤢ Pillow lava, Semail ophiolite — Wadi Jizzi, Oman Lionel Duchoiselle · CC BY-SA 3.0 Identifications and locations are as stated by each source and are pending confirmation by our geologist.
How to recognise it Fine-grained dark rock forming rounded, pillow-shaped bodies.
How it formed Basalt lava erupted under the sea and chilled quickly into pillows.
In Oman Pillow lavas form the upper part of the ophiolite sequence; pillow lavas are also a stop on our Jabal Akhdar route.
Why it matters Pillow shapes prove an eruption happened under water. Sédimentaires
Calcaire Pale, fine-grained rock Shell fragments Calcaire about 5 cm (illustrative) HAND SPECIMEN · SCIENTIFIC ILLUSTRATION Illustration scientifique of a typical limestone hand specimen, with the features that identify it — not a photograph. An approved specimen photograph is still needed.
How to recognise it Pale grey to cream rock, often containing fossils.
How it formed Built up from calcium carbonate in warm, shallow seas.
In Oman Thick Permian–Cretaceous limestones (Hajar Supergroup) form much of Jabal Akhdar; younger Tertiary limestones occur around Muscat.
Why it matters Each layer records the seas that once covered Oman.
Key minerals Calcite
See it with GeoAstro Tertiary limestone — Muscat route Fossil
Corail fossile Honeycomb pattern of coral cells Corail fossile about 5 cm (illustrative) HAND SPECIMEN · SCIENTIFIC ILLUSTRATION Illustration scientifique of a typical fossil coral hand specimen, with the features that identify it — not a photograph. An approved specimen photograph is still needed.
How to recognise it Honeycomb or branching patterns preserved in limestone.
How it formed Remains of corals that lived on the shallow sea floor.
In Oman Fossil corals occur in Oman’s limestones.
Why it matters Corals show that the area was once a warm, shallow sea. Fossil
Stromatolite Fine wavy layers Domed growth Stromatolite about 5 cm (illustrative) HAND SPECIMEN · SCIENTIFIC ILLUSTRATION Illustration scientifique of a typical stromatolite hand specimen, with the features that identify it — not a photograph. An approved specimen photograph is still needed.
How to recognise it Fine wavy or domed layers in carbonate rock.
How it formed Built layer by layer by microbial mats that trapped sediment.
In Oman Occur in Oman’s Neoproterozoic carbonate rocks.
Why it matters Among the oldest traces of life on Earth.
See it with GeoAstro Geology and cultural hike — Jabal Akhdar route Sédimentaires
Dépôt glaciaire Pebbles and boulders of many sizes Fine-grained matrix Dépôt glaciaire about 5 cm (illustrative) HAND SPECIMEN · SCIENTIFIC ILLUSTRATION Illustration scientifique of a typical glacial deposit hand specimen, with the features that identify it — not a photograph. An approved specimen photograph is still needed.
How to recognise it Pebbles and boulders of mixed sizes in a fine-grained matrix.
How it formed Debris carried and dropped by glaciers.
In Oman Neoproterozoic (Cryogenian) glacial deposits are preserved in Oman, including diamictites of the Abu Mahara Group on the Saiq Plateau of Jabal Akhdar.
Why it matters Evidence for the “Snowball Earth” ice ages.
See it with GeoAstro Geology and cultural hike — Jabal Akhdar route Métamorphiques
Éclogite Round red garnet crystals Green pyroxene (omphacite) Éclogite about 5 cm (illustrative) HAND SPECIMEN · SCIENTIFIC ILLUSTRATION Illustration scientifique of a typical eclogite hand specimen, with the features that identify it — not a photograph. An approved specimen photograph is still needed.
How to recognise it Green rock studded with red garnet crystals.
How it formed Formed at very high pressure, deep in a subduction zone.
In Oman High-pressure rocks of the Saih Hatat area, including As Sifah, formed in the Late Cretaceous (about 80 million years ago).
Why it matters Shows that rocks from the edge of Arabia went deep into the Earth and came back.
Key minerals Garnet · Omphacite
See it with GeoAstro Sifah eclogite — Muscat route Métamorphiques
Roches métamorphiques (schiste) Shiny minerals in aligned layers (foliation) Roches métamorphiques (schiste) about 5 cm (illustrative) HAND SPECIMEN · SCIENTIFIC ILLUSTRATION Illustration scientifique of a typical metamorphic rocks (schist) hand specimen, with the features that identify it — not a photograph. An approved specimen photograph is still needed.
How to recognise it Rocks with a layered, often shiny foliation.
How it formed Existing rocks changed by heat and pressure without melting.
In Oman The Saih Hatat area near Muscat contains metamorphic rocks formed during Late Cretaceous subduction.
Why it matters They record the pressures and temperatures rocks experienced. Sédimentaires
Travertin Banded layers Small pores Travertin about 5 cm (illustrative) HAND SPECIMEN · SCIENTIFIC ILLUSTRATION Illustration scientifique of a typical travertine hand specimen, with the features that identify it — not a photograph. An approved specimen photograph is still needed.
How to recognise it Pale, porous or banded carbonate rock.
How it formed Carbonate minerals precipitated from spring water.
In Oman Forms today where groundwater reacts with mantle peridotite; on the Saiq Plateau of Jabal Akhdar, older spring travertine was deposited where water emerged from limestone.
Why it matters A natural example of rocks capturing carbon dioxide.
See it with GeoAstro Geology and cultural hike — Jabal Akhdar route Structure
Pli en fourreau
Squeezed Squeezed Hinge: where the beds bend most sharply Anticline: beds fold upward into an arch Limb: the sloping side Syncline: beds fold down into a trough Thin alternating beds make the folds easy to see LEGEND · NOT TO SCALE Light bed Darker bed FOLDED STRATA · CONCEPT SKETCH Illustration scientifique — Concept sketch of thin beds squeezed into folds. A sheath fold is a more intensely sheared, tube-shaped fold (see the slider). Not a photograph. An approved photograph is still needed.
How to recognise it A tube- or cone-shaped fold in strongly deformed rock.
How it formed Formed when rock is intensely sheared and stretched.
In Oman Sheath folds occur in the deformed rocks of the Saih Hatat region near Muscat, including spectacular folds in Permian Saiq Formation limestones at Wadi Al Mayh.
Why it matters Records the extreme deformation as rocks returned from depth.
See it with GeoAstro Wadi Al Mayh — Muscat route Mineral
Olivine Olive-green glassy grains Olivine about 5 cm (illustrative) HAND SPECIMEN · SCIENTIFIC ILLUSTRATION Illustration scientifique of a typical olivine hand specimen, with the features that identify it — not a photograph. An approved specimen photograph is still needed.
How to recognise it Olive-green glassy grains.
How it formed A main mineral of Earth’s upper mantle.
In Oman The main mineral of the ophiolite’s mantle peridotite.
Why it matters Reacts with water and CO₂, forming carbonate minerals. Mineral
Grenat Deep red rounded crystals Grenat about 5 cm (illustrative) HAND SPECIMEN · SCIENTIFIC ILLUSTRATION Illustration scientifique of a typical garnet hand specimen, with the features that identify it — not a photograph. An approved specimen photograph is still needed.
How to recognise it Deep red, rounded crystals.
How it formed Grows in rocks under high pressure and temperature.
In Oman A key mineral of the As Sifah eclogites.
Why it matters Its chemistry helps geologists work out how deep rocks were buried. Interprétation publiée Brouillon · en attente de validation par un géologue Sources : Searle et al. 1994 Mineral
Calcite Rhomb-shaped crystals White to colourless Calcite about 5 cm (illustrative) HAND SPECIMEN · SCIENTIFIC ILLUSTRATION Illustration scientifique of a typical calcite hand specimen, with the features that identify it — not a photograph. An approved specimen photograph is still needed.
How to recognise it White to colourless mineral, the main component of limestone and travertine.
How it formed Precipitates from sea water, spring water or living organisms.
In Oman Makes up Oman’s limestones and the travertine forming today.
Why it matters Records ancient seas and modern carbon capture. Vivez-le en vrai
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