Learn · Module A
Rock Identification Lab
Look closely, ask the right questions and sort Oman’s rocks into their families — the way geologists do in the field.
Las explicaciones científicas detalladas del Geo Lab siguen en inglés. Se traducirán cuando nuestro geólogo las haya aprobado.
The specimen collection
15 rocks, minerals and fossils from Oman’s story
2 are shown with real photographs — GeoAstro’s own or licensed specimens, credited in the Rock Explorer. The rest use a labelled Ilustración científica until a suitable photograph is approved.
- ÍgneasPeridotitaIllustration · photo needed
- ÍgneasDolerita (diques laminares)Illustration · photo needed
- SedimentariasCalizaIllustration · photo needed
- FossilCoral fósilIllustration · photo needed
- FossilEstromatolitoIllustration · photo needed
- SedimentariasDepósito glaciarIllustration · photo needed
- MetamórficasEclogitaIllustration · photo needed
- MetamórficasRocas metamórficas (esquisto)Illustration · photo needed
- SedimentariasTravertinoIllustration · photo needed
- StructurePliegue en vainaIllustration · photo needed
- MineralOlivinoIllustration · photo needed
- MineralGranateIllustration · photo needed
- MineralCalcitaIllustration · photo needed
Identify a rock
Answer what you see — the key does the rest
Geologists identify rocks by looking closely: crystals or grains, layers, fossils and colour. Follow the questions as you would in the field.
Pregunta 1
What do you notice first about the rock?
Look at the whole rock first, then up close with a hand lens.
Pregunta 1
What kind of pattern can you see?
Pregunta 1
Is it porous or banded, like a spring deposit?
Geologists test these rocks with a drop of dilute acid: calcite fizzes. Only your guide does this test.
Pregunta 1
How are the crystals arranged?
Pregunta 1
How big are the crystals?
Crystal size tells you how fast the magma cooled.
Your rock is probably
Coral fósil
Fossil
- Looks like
- Honeycomb or branching patterns preserved in limestone.
- How it forms
- Remains of corals that lived on the shallow sea floor.
- In Oman
- Fossil corals occur in Oman’s limestones.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Glennie et al. 1974, Searle 2019
Open in the Rock Explorer Your rock is probably
Estromatolito
Fossil
- Looks like
- Fine wavy or domed layers in carbonate rock.
- How it forms
- Built layer by layer by microbial mats that trapped sediment.
- In Oman
- Occur in Oman’s Neoproterozoic carbonate rocks.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Grotzinger & Knoll 1999, Allen 2007
Open in the Rock Explorer Your rock is probably
Caliza
Sedimentarias
- Looks like
- Pale grey to cream rock, often containing fossils.
- How it forms
- 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.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Glennie et al. 1974, Searle 2019
Open in the Rock Explorer Your rock is probably
Depósito glaciar
Sedimentarias
- Looks like
- Pebbles and boulders of mixed sizes in a fine-grained matrix.
- How it forms
- 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.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Allen 2007, Al-Kindy & Al-Belushi 2010 (GSO guide)
Open in the Rock Explorer Your rock is probably
Rocas metamórficas (esquisto)
Metamórficas
- Looks like
- Rocks with a layered, often shiny foliation.
- How it forms
- 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.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Searle et al. 2004, Searle et al. 1994
Open in the Rock Explorer Your rock is probably
Eclogita
Metamórficas
- Looks like
- Green rock studded with red garnet crystals.
- How it forms
- 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).
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Searle et al. 1994, Warren et al. 2003
Open in the Rock Explorer Your rock is probably
Gabro
Ígneas
- Looks like
- Coarse-grained, speckled dark and light crystals.
- How it forms
- 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.
Your rock is probably
Dolerita (diques laminares)
Ígneas
- Looks like
- Medium-grained dark rock in parallel vertical sheets.
- How it forms
- Magma that filled cracks as the sea floor pulled apart, feeding the lavas above.
- In Oman
- The sheeted dyke complex of the Samail ophiolite.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Penrose 1972, Nicolas et al. 2000
Open in the Rock Explorer Your rock is probably
Basalto y lavas almohadilladas
Ígneas
- Looks like
- Fine-grained dark rock forming rounded, pillow-shaped bodies.
- How it forms
- 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.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Penrose 1972, Searle 2019
Open in the Rock Explorer Your rock is probably
Peridotita
Ígneas
- Looks like
- Dense, dark green rock that often weathers to a rusty brown surface.
- How it forms
- Formed in Earth’s upper mantle, below the oceanic crust.
- In Oman
- Forms the mantle section of the Samail ophiolite in the Oman Mountains.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Penrose 1972, Nicolas et al. 2000, Kelemen & Matter 2008
Open in the Rock Explorer Your rock is probably
Travertino
Sedimentarias
- Looks like
- Pale, porous or banded carbonate rock.
- How it forms
- 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.
MedidoBorrador · pendiente de revisión geológicaFuentes: Kelemen & Matter 2008, Al-Kindy & Al-Belushi 2010 (GSO guide)
Open in the Rock Explorer Still possible · 11
- Coral fósil
- Estromatolito
- Caliza
- Depósito glaciar
- Rocas metamórficas (esquisto)
- Eclogita
- Dolerita (diques laminares)
- Peridotita
- Travertino
A real identification needs a hand lens, a fresh surface and simple tests — ask your GeoAstro guide in the field.
Look closely
Use the lens like a field geologist
Move the magnifier over each specimen — with your mouse, your finger or the arrow keys — then answer what you observe.
Challenge 1 of 6
Move the lens over the rock. Can you see separate crystals?
Gabbro cooled slowly deep in the crust, so its crystals had time to grow large.
Challenge 2 of 6
What colour are the round crystals scattered through the green rock?
The red crystals are garnet, a mineral that grows at high pressure.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Grotzinger & Jordan 2014, Searle et al. 1994
Challenge 3 of 6
How are the mineral grains arranged?
Heat and pressure line the minerals up, giving a layered texture called foliation.
Challenge 4 of 6
Are the pebbles all the same size?
Glaciers carry and drop debris of every size together, so glacial deposits are poorly sorted.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Grotzinger & Jordan 2014, Allen 2007
Challenge 5 of 6
Look at the rock face the guide is pointing to. Which shapes tell you how this lava erupted?
Rounded pillows form when lava erupts under water and its surface chills instantly.
Challenge 6 of 6
Look closely at the cut surface. What does the pattern come from?
Honeycomb or branching patterns preserved in limestone are the remains of corals.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Glennie et al. 1974, Searle 2019
Classification activity
Sort the rocks into their families
Tap a specimen, then tap the family you think it belongs to. Think about how each rock formed.
Elige una muestra para empezar.
0 of 9 sorted
Educational comparisons
Similar at first sight, different stories
Comparing rocks side by side is how geologists learn what each clue means.
Gabro
Dolerita (diques laminares)
Basalto y lavas almohadilladas
Gabbro, dolerite and basalt can form from similar magma. What changes is how fast it cooled: slowly deep in the crust gives large crystals; quickly on the sea floor gives tiny ones.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Grotzinger & Jordan 2014, Penrose 1972
Caliza
Travertino
Both are made mostly of calcite. Limestone built up in warm, shallow seas; travertine precipitates from spring water.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Glennie et al. 1974, Kelemen & Matter 2008
Rocas metamórficas (esquisto)
Eclogita
Both are metamorphic rocks. Schist shows minerals lined up in layers; eclogite formed at very high pressure, deep in a subduction zone, and contains red garnet.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Grotzinger & Jordan 2014, Searle et al. 1994
Coral fósil
Estromatolito
Fossil corals are the remains of animals that lived on the shallow sea floor. Stromatolites were built layer by layer by microbial mats — among the oldest traces of life.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Glennie et al. 1974, Grotzinger & Knoll 1999
Compare any two specimens
Ígneas
Peridotita
- Looks like
- Dense, dark green rock that often weathers to a rusty brown surface.
- How it forms
- Formed in Earth’s upper mantle, below the oceanic crust.
- Minerals
- Olivine, Pyroxene, Serpentine (alteration)
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Penrose 1972, Nicolas et al. 2000, Kelemen & Matter 2008
Ígneas
Gabro
- Looks like
- Coarse-grained, speckled dark and light crystals.
- How it forms
- Magma that cooled slowly deep in the oceanic crust.
- Minerals
- Plagioclase, Pyroxene
Ígneas
Dolerita (diques laminares)
- Looks like
- Medium-grained dark rock in parallel vertical sheets.
- How it forms
- Magma that filled cracks as the sea floor pulled apart, feeding the lavas above.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Penrose 1972, Nicolas et al. 2000
Ígneas
Basalto y lavas almohadilladas
- Looks like
- Fine-grained dark rock forming rounded, pillow-shaped bodies.
- How it forms
- Basalt lava erupted under the sea and chilled quickly into pillows.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Penrose 1972, Searle 2019
Sedimentarias
Caliza
- Looks like
- Pale grey to cream rock, often containing fossils.
- How it forms
- Built up from calcium carbonate in warm, shallow seas.
- Minerals
- Calcita
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Glennie et al. 1974, Searle 2019
Fossil
Coral fósil
- Looks like
- Honeycomb or branching patterns preserved in limestone.
- How it forms
- Remains of corals that lived on the shallow sea floor.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Glennie et al. 1974, Searle 2019
Fossil
Estromatolito
- Looks like
- Fine wavy or domed layers in carbonate rock.
- How it forms
- Built layer by layer by microbial mats that trapped sediment.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Grotzinger & Knoll 1999, Allen 2007
Sedimentarias
Depósito glaciar
- Looks like
- Pebbles and boulders of mixed sizes in a fine-grained matrix.
- How it forms
- Debris carried and dropped by glaciers.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Allen 2007, Al-Kindy & Al-Belushi 2010 (GSO guide)
Metamórficas
Eclogita
- Looks like
- Green rock studded with red garnet crystals.
- How it forms
- Formed at very high pressure, deep in a subduction zone.
- Minerals
- Garnet, Omphacite
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Searle et al. 1994, Warren et al. 2003
Metamórficas
Rocas metamórficas (esquisto)
- Looks like
- Rocks with a layered, often shiny foliation.
- How it forms
- Existing rocks changed by heat and pressure without melting.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Searle et al. 2004, Searle et al. 1994
Sedimentarias
Travertino
- Looks like
- Pale, porous or banded carbonate rock.
- How it forms
- Carbonate minerals precipitated from spring water.
MedidoBorrador · pendiente de revisión geológicaFuentes: Kelemen & Matter 2008, Al-Kindy & Al-Belushi 2010 (GSO guide)
Structure
Pliegue en vaina
- Looks like
- A tube- or cone-shaped fold in strongly deformed rock.
- How it forms
- Formed when rock is intensely sheared and stretched.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Searle et al. 2004, Al Kindi 2017 (GSO guide)
Mineral
Olivino
- Looks like
- Olive-green glassy grains.
- How it forms
- A main mineral of Earth’s upper mantle.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Nicolas et al. 2000, Kelemen & Matter 2008
Mineral
Granate
- Looks like
- Deep red, rounded crystals.
- How it forms
- Grows in rocks under high pressure and temperature.
Mineral
Calcita
- Looks like
- White to colourless mineral, the main component of limestone and travertine.
- How it forms
- Precipitates from sea water, spring water or living organisms.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Glennie et al. 1974, Kelemen & Matter 2008
Ígneas
Peridotita
- Looks like
- Dense, dark green rock that often weathers to a rusty brown surface.
- How it forms
- Formed in Earth’s upper mantle, below the oceanic crust.
- Minerals
- Olivine, Pyroxene, Serpentine (alteration)
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Penrose 1972, Nicolas et al. 2000, Kelemen & Matter 2008
Ígneas
Gabro
- Looks like
- Coarse-grained, speckled dark and light crystals.
- How it forms
- Magma that cooled slowly deep in the oceanic crust.
- Minerals
- Plagioclase, Pyroxene
Ígneas
Dolerita (diques laminares)
- Looks like
- Medium-grained dark rock in parallel vertical sheets.
- How it forms
- Magma that filled cracks as the sea floor pulled apart, feeding the lavas above.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Penrose 1972, Nicolas et al. 2000
Ígneas
Basalto y lavas almohadilladas
- Looks like
- Fine-grained dark rock forming rounded, pillow-shaped bodies.
- How it forms
- Basalt lava erupted under the sea and chilled quickly into pillows.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Penrose 1972, Searle 2019
Sedimentarias
Caliza
- Looks like
- Pale grey to cream rock, often containing fossils.
- How it forms
- Built up from calcium carbonate in warm, shallow seas.
- Minerals
- Calcita
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Glennie et al. 1974, Searle 2019
Fossil
Coral fósil
- Looks like
- Honeycomb or branching patterns preserved in limestone.
- How it forms
- Remains of corals that lived on the shallow sea floor.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Glennie et al. 1974, Searle 2019
Fossil
Estromatolito
- Looks like
- Fine wavy or domed layers in carbonate rock.
- How it forms
- Built layer by layer by microbial mats that trapped sediment.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Grotzinger & Knoll 1999, Allen 2007
Sedimentarias
Depósito glaciar
- Looks like
- Pebbles and boulders of mixed sizes in a fine-grained matrix.
- How it forms
- Debris carried and dropped by glaciers.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Allen 2007, Al-Kindy & Al-Belushi 2010 (GSO guide)
Metamórficas
Eclogita
- Looks like
- Green rock studded with red garnet crystals.
- How it forms
- Formed at very high pressure, deep in a subduction zone.
- Minerals
- Garnet, Omphacite
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Searle et al. 1994, Warren et al. 2003
Metamórficas
Rocas metamórficas (esquisto)
- Looks like
- Rocks with a layered, often shiny foliation.
- How it forms
- Existing rocks changed by heat and pressure without melting.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Searle et al. 2004, Searle et al. 1994
Sedimentarias
Travertino
- Looks like
- Pale, porous or banded carbonate rock.
- How it forms
- Carbonate minerals precipitated from spring water.
MedidoBorrador · pendiente de revisión geológicaFuentes: Kelemen & Matter 2008, Al-Kindy & Al-Belushi 2010 (GSO guide)
Structure
Pliegue en vaina
- Looks like
- A tube- or cone-shaped fold in strongly deformed rock.
- How it forms
- Formed when rock is intensely sheared and stretched.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Searle et al. 2004, Al Kindi 2017 (GSO guide)
Mineral
Olivino
- Looks like
- Olive-green glassy grains.
- How it forms
- A main mineral of Earth’s upper mantle.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Nicolas et al. 2000, Kelemen & Matter 2008
Mineral
Granate
- Looks like
- Deep red, rounded crystals.
- How it forms
- Grows in rocks under high pressure and temperature.
Mineral
Calcita
- Looks like
- White to colourless mineral, the main component of limestone and travertine.
- How it forms
- Precipitates from sea water, spring water or living organisms.
Interpretación publicadaBorrador · pendiente de revisión geológicaFuentes: Glennie et al. 1974, Kelemen & Matter 2008
Aprende en el campo
Lleva la clase al aire libre con GeoAstro Oman
Programa de geología para colegios
Preparación en el aula, una salida de campo guiada y actividades posteriores para tus estudiantes.
Reserva el programa de geología escolarsolicitud de reserva por WhatsApp (abre WhatsApp en una nueva pestaña)Ruta geológica de Mascate
Siete paradas, de la ofiolita a la eclogita de Sifah.
Reserva la ruta geológica de Mascatesolicitud de reserva por WhatsApp (abre WhatsApp en una nueva pestaña)Ruta geológica del Jabal Akhdar
Cinco paradas, de Coral Park a la caminata cultural en el pueblo de Al Ain.
Reserva la ruta geológica del Jabal Akhdarsolicitud de reserva por WhatsApp (abre WhatsApp en una nueva pestaña)Experiencia de campo universitaria
Descripción de campo, estructuras y literatura publicada, en las montañas de Omán.
Solicita una experiencia de campo universitariasolicitud de reserva por WhatsApp (abre WhatsApp en una nueva pestaña)
Un mensaje de WhatsApp es una consulta, no una reserva confirmada. Nuestro equipo te responderá para confirmar la disponibilidad, los detalles y el programa. Las experiencias dependen del cielo y del tiempo.