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.
Le spiegazioni scientifiche dettagliate del Geo Lab sono ancora in inglese. Saranno tradotte dopo l’approvazione del nostro geologo.
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 Illustrazione scientifica until a suitable photograph is approved.
- IgneePeridotiteIllustration · photo needed
- IgneeDolerite (dicchi a lamine)Illustration · photo needed
- SedimentarieCalcareIllustration · photo needed
- FossilCorallo fossileIllustration · photo needed
- FossilStromatoliteIllustration · photo needed
- SedimentarieDeposito glacialeIllustration · photo needed
- MetamorficheEclogiteIllustration · photo needed
- MetamorficheRocce metamorfiche (scisto)Illustration · photo needed
- SedimentarieTravertinoIllustration · photo needed
- StructurePiega a guainaIllustration · photo needed
- MineralOlivinaIllustration · photo needed
- MineralGranatoIllustration · photo needed
- MineralCalciteIllustration · 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.
Domanda 1
What do you notice first about the rock?
Look at the whole rock first, then up close with a hand lens.
Domanda 1
What kind of pattern can you see?
Domanda 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.
Domanda 1
How are the crystals arranged?
Domanda 1
How big are the crystals?
Crystal size tells you how fast the magma cooled.
Your rock is probably
Corallo fossile
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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Glennie et al. 1974, Searle 2019
Open in the Rock Explorer Your rock is probably
Stromatolite
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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Grotzinger & Knoll 1999, Allen 2007
Open in the Rock Explorer Your rock is probably
Calcare
Sedimentarie
- 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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Glennie et al. 1974, Searle 2019
Open in the Rock Explorer Your rock is probably
Deposito glaciale
Sedimentarie
- 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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Allen 2007, Al-Kindy & Al-Belushi 2010 (GSO guide)
Open in the Rock Explorer Your rock is probably
Rocce metamorfiche (scisto)
Metamorfiche
- 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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Searle et al. 2004, Searle et al. 1994
Open in the Rock Explorer Your rock is probably
Eclogite
Metamorfiche
- 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).
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Searle et al. 1994, Warren et al. 2003
Open in the Rock Explorer Your rock is probably
Gabbro
Ignee
- 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
Dolerite (dicchi a lamine)
Ignee
- 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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Penrose 1972, Nicolas et al. 2000
Open in the Rock Explorer Your rock is probably
Basalto e lave a cuscino
Ignee
- 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.
Your rock is probably
Peridotite
Ignee
- 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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Penrose 1972, Nicolas et al. 2000, Kelemen & Matter 2008
Open in the Rock Explorer Your rock is probably
Travertino
Sedimentarie
- 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.
MisuratoBozza · in attesa di revisione geologicaFonti: Kelemen & Matter 2008, Al-Kindy & Al-Belushi 2010 (GSO guide)
Open in the Rock Explorer Still possible · 11
- Corallo fossile
- Stromatolite
- Calcare
- Deposito glaciale
- Rocce metamorfiche (scisto)
- Eclogite
- Dolerite (dicchi a lamine)
- Peridotite
- 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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: 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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: 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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: 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.
Scegli un campione per iniziare.
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.
Gabbro
Dolerite (dicchi a lamine)
Basalto e lave a cuscino
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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Grotzinger & Jordan 2014, Penrose 1972
Calcare
Travertino
Both are made mostly of calcite. Limestone built up in warm, shallow seas; travertine precipitates from spring water.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Glennie et al. 1974, Kelemen & Matter 2008
Rocce metamorfiche (scisto)
Eclogite
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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Grotzinger & Jordan 2014, Searle et al. 1994
Corallo fossile
Stromatolite
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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Glennie et al. 1974, Grotzinger & Knoll 1999
Compare any two specimens
Ignee
Peridotite
- 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)
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Penrose 1972, Nicolas et al. 2000, Kelemen & Matter 2008
Ignee
Gabbro
- Looks like
- Coarse-grained, speckled dark and light crystals.
- How it forms
- Magma that cooled slowly deep in the oceanic crust.
- Minerals
- Plagioclase, Pyroxene
Ignee
Dolerite (dicchi a lamine)
- 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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Penrose 1972, Nicolas et al. 2000
Ignee
Basalto e lave a cuscino
- 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.
Sedimentarie
Calcare
- Looks like
- Pale grey to cream rock, often containing fossils.
- How it forms
- Built up from calcium carbonate in warm, shallow seas.
- Minerals
- Calcite
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Glennie et al. 1974, Searle 2019
Fossil
Corallo fossile
- Looks like
- Honeycomb or branching patterns preserved in limestone.
- How it forms
- Remains of corals that lived on the shallow sea floor.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Glennie et al. 1974, Searle 2019
Fossil
Stromatolite
- Looks like
- Fine wavy or domed layers in carbonate rock.
- How it forms
- Built layer by layer by microbial mats that trapped sediment.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Grotzinger & Knoll 1999, Allen 2007
Sedimentarie
Deposito glaciale
- Looks like
- Pebbles and boulders of mixed sizes in a fine-grained matrix.
- How it forms
- Debris carried and dropped by glaciers.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Allen 2007, Al-Kindy & Al-Belushi 2010 (GSO guide)
Metamorfiche
Eclogite
- 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
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Searle et al. 1994, Warren et al. 2003
Metamorfiche
Rocce metamorfiche (scisto)
- Looks like
- Rocks with a layered, often shiny foliation.
- How it forms
- Existing rocks changed by heat and pressure without melting.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Searle et al. 2004, Searle et al. 1994
Sedimentarie
Travertino
- Looks like
- Pale, porous or banded carbonate rock.
- How it forms
- Carbonate minerals precipitated from spring water.
MisuratoBozza · in attesa di revisione geologicaFonti: Kelemen & Matter 2008, Al-Kindy & Al-Belushi 2010 (GSO guide)
Structure
Piega a guaina
- Looks like
- A tube- or cone-shaped fold in strongly deformed rock.
- How it forms
- Formed when rock is intensely sheared and stretched.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Searle et al. 2004, Al Kindi 2017 (GSO guide)
Mineral
Olivina
- Looks like
- Olive-green glassy grains.
- How it forms
- A main mineral of Earth’s upper mantle.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Nicolas et al. 2000, Kelemen & Matter 2008
Mineral
Granato
- Looks like
- Deep red, rounded crystals.
- How it forms
- Grows in rocks under high pressure and temperature.
Mineral
Calcite
- 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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Glennie et al. 1974, Kelemen & Matter 2008
Ignee
Peridotite
- 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)
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Penrose 1972, Nicolas et al. 2000, Kelemen & Matter 2008
Ignee
Gabbro
- Looks like
- Coarse-grained, speckled dark and light crystals.
- How it forms
- Magma that cooled slowly deep in the oceanic crust.
- Minerals
- Plagioclase, Pyroxene
Ignee
Dolerite (dicchi a lamine)
- 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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Penrose 1972, Nicolas et al. 2000
Ignee
Basalto e lave a cuscino
- 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.
Sedimentarie
Calcare
- Looks like
- Pale grey to cream rock, often containing fossils.
- How it forms
- Built up from calcium carbonate in warm, shallow seas.
- Minerals
- Calcite
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Glennie et al. 1974, Searle 2019
Fossil
Corallo fossile
- Looks like
- Honeycomb or branching patterns preserved in limestone.
- How it forms
- Remains of corals that lived on the shallow sea floor.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Glennie et al. 1974, Searle 2019
Fossil
Stromatolite
- Looks like
- Fine wavy or domed layers in carbonate rock.
- How it forms
- Built layer by layer by microbial mats that trapped sediment.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Grotzinger & Knoll 1999, Allen 2007
Sedimentarie
Deposito glaciale
- Looks like
- Pebbles and boulders of mixed sizes in a fine-grained matrix.
- How it forms
- Debris carried and dropped by glaciers.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Allen 2007, Al-Kindy & Al-Belushi 2010 (GSO guide)
Metamorfiche
Eclogite
- 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
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Searle et al. 1994, Warren et al. 2003
Metamorfiche
Rocce metamorfiche (scisto)
- Looks like
- Rocks with a layered, often shiny foliation.
- How it forms
- Existing rocks changed by heat and pressure without melting.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Searle et al. 2004, Searle et al. 1994
Sedimentarie
Travertino
- Looks like
- Pale, porous or banded carbonate rock.
- How it forms
- Carbonate minerals precipitated from spring water.
MisuratoBozza · in attesa di revisione geologicaFonti: Kelemen & Matter 2008, Al-Kindy & Al-Belushi 2010 (GSO guide)
Structure
Piega a guaina
- Looks like
- A tube- or cone-shaped fold in strongly deformed rock.
- How it forms
- Formed when rock is intensely sheared and stretched.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Searle et al. 2004, Al Kindi 2017 (GSO guide)
Mineral
Olivina
- Looks like
- Olive-green glassy grains.
- How it forms
- A main mineral of Earth’s upper mantle.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Nicolas et al. 2000, Kelemen & Matter 2008
Mineral
Granato
- Looks like
- Deep red, rounded crystals.
- How it forms
- Grows in rocks under high pressure and temperature.
Mineral
Calcite
- 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.
Interpretazione pubblicataBozza · in attesa di revisione geologicaFonti: Glennie et al. 1974, Kelemen & Matter 2008
Impara sul campo
Porta la lezione all’aperto con GeoAstro Oman
Programma di geologia per le scuole
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Prenota il programma di geologia per la scuolarichiesta di prenotazione via WhatsApp (apre WhatsApp in una nuova scheda)Tour geologico di Mascate
Sette tappe, dall’ofiolite all’eclogite di Sifah.
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Cinque tappe, da Coral Park all’escursione culturale nel villaggio di Al Ain.
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Descrizione sul campo, strutture e letteratura pubblicata, tra le montagne dell’Oman.
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