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.
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 رسم علمي توضيحي until a suitable photograph is approved.
- الناريةالبيريدوتيتIllustration · photo needed
- الناريةالدوليريت (القواطع الصفائحية)Illustration · photo needed
- الرسوبيةالحجر الجيريIllustration · photo needed
- أحفورةالمرجان المتحجّرIllustration · photo needed
- أحفورةالستروماتوليتIllustration · photo needed
- الرسوبيةرواسب جليديةIllustration · photo needed
- المتحوّلةالإكلوجيتIllustration · photo needed
- المتحوّلةالصخور المتحوّلة (الشيست)Illustration · photo needed
- الرسوبيةالترافرتينIllustration · photo needed
- Structureطيّة غِمديةIllustration · photo needed
- MineralالأوليفينIllustration · photo needed
- Mineralالعقيق (الغارنت)Illustration · photo needed
- MineralالكالسيتIllustration · 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.
سؤال 1
What do you notice first about the rock?
Look at the whole rock first, then up close with a hand lens.
سؤال 1
What kind of pattern can you see?
سؤال 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.
سؤال 1
How are the crystals arranged?
سؤال 1
How big are the crystals?
Crystal size tells you how fast the magma cooled.
Your rock is probably
المرجان المتحجّر
أحفورة
- 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.
Your rock is probably
الستروماتوليت
أحفورة
- 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.
Your rock is probably
الحجر الجيري
الرسوبية
- 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.
Your rock is probably
رواسب جليدية
الرسوبية
- 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.
Your rock is probably
الصخور المتحوّلة (الشيست)
المتحوّلة
- 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.
Your rock is probably
الإكلوجيت
المتحوّلة
- 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).
Your rock is probably
الغابرو
النارية
- 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
الدوليريت (القواطع الصفائحية)
النارية
- 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.
Your rock is probably
البازلت والحمم الوسائدية
النارية
- 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
البيريدوتيت
النارية
- 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.
Your rock is probably
الترافرتين
الرسوبية
- 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.
Still possible · 11
- المرجان المتحجّر
- الستروماتوليت
- الحجر الجيري
- رواسب جليدية
- الصخور المتحوّلة (الشيست)
- الإكلوجيت
- الدوليريت (القواطع الصفائحية)
- البيريدوتيت
- الترافرتين
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.
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.
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.
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.
اختر عيّنة للبدء.
Educational comparisons
Similar at first sight, different stories
Comparing rocks side by side is how geologists learn what each clue means.
الغابرو
الدوليريت (القواطع الصفائحية)
البازلت والحمم الوسائدية
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.
الحجر الجيري
الترافرتين
Both are made mostly of calcite. Limestone built up in warm, shallow seas; travertine precipitates from spring water.
الصخور المتحوّلة (الشيست)
الإكلوجيت
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.
المرجان المتحجّر
الستروماتوليت
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.
Compare any two specimens
النارية
البيريدوتيت
- 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)
النارية
الغابرو
- Looks like
- Coarse-grained, speckled dark and light crystals.
- How it forms
- Magma that cooled slowly deep in the oceanic crust.
- Minerals
- Plagioclase, Pyroxene
النارية
الدوليريت (القواطع الصفائحية)
- 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.
النارية
البازلت والحمم الوسائدية
- 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.
الرسوبية
الحجر الجيري
- Looks like
- Pale grey to cream rock, often containing fossils.
- How it forms
- Built up from calcium carbonate in warm, shallow seas.
- Minerals
- الكالسيت
أحفورة
المرجان المتحجّر
- Looks like
- Honeycomb or branching patterns preserved in limestone.
- How it forms
- Remains of corals that lived on the shallow sea floor.
أحفورة
الستروماتوليت
- Looks like
- Fine wavy or domed layers in carbonate rock.
- How it forms
- Built layer by layer by microbial mats that trapped sediment.
الرسوبية
رواسب جليدية
- Looks like
- Pebbles and boulders of mixed sizes in a fine-grained matrix.
- How it forms
- Debris carried and dropped by glaciers.
المتحوّلة
الإكلوجيت
- 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
المتحوّلة
الصخور المتحوّلة (الشيست)
- Looks like
- Rocks with a layered, often shiny foliation.
- How it forms
- Existing rocks changed by heat and pressure without melting.
الرسوبية
الترافرتين
- Looks like
- Pale, porous or banded carbonate rock.
- How it forms
- Carbonate minerals precipitated from spring water.
Structure
طيّة غِمدية
- Looks like
- A tube- or cone-shaped fold in strongly deformed rock.
- How it forms
- Formed when rock is intensely sheared and stretched.
Mineral
الأوليفين
- Looks like
- Olive-green glassy grains.
- How it forms
- A main mineral of Earth’s upper mantle.
Mineral
العقيق (الغارنت)
- Looks like
- Deep red, rounded crystals.
- How it forms
- Grows in rocks under high pressure and temperature.
Mineral
الكالسيت
- 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.
النارية
البيريدوتيت
- 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)
النارية
الغابرو
- Looks like
- Coarse-grained, speckled dark and light crystals.
- How it forms
- Magma that cooled slowly deep in the oceanic crust.
- Minerals
- Plagioclase, Pyroxene
النارية
الدوليريت (القواطع الصفائحية)
- 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.
النارية
البازلت والحمم الوسائدية
- 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.
الرسوبية
الحجر الجيري
- Looks like
- Pale grey to cream rock, often containing fossils.
- How it forms
- Built up from calcium carbonate in warm, shallow seas.
- Minerals
- الكالسيت
أحفورة
المرجان المتحجّر
- Looks like
- Honeycomb or branching patterns preserved in limestone.
- How it forms
- Remains of corals that lived on the shallow sea floor.
أحفورة
الستروماتوليت
- Looks like
- Fine wavy or domed layers in carbonate rock.
- How it forms
- Built layer by layer by microbial mats that trapped sediment.
الرسوبية
رواسب جليدية
- Looks like
- Pebbles and boulders of mixed sizes in a fine-grained matrix.
- How it forms
- Debris carried and dropped by glaciers.
المتحوّلة
الإكلوجيت
- 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
المتحوّلة
الصخور المتحوّلة (الشيست)
- Looks like
- Rocks with a layered, often shiny foliation.
- How it forms
- Existing rocks changed by heat and pressure without melting.
الرسوبية
الترافرتين
- Looks like
- Pale, porous or banded carbonate rock.
- How it forms
- Carbonate minerals precipitated from spring water.
Structure
طيّة غِمدية
- Looks like
- A tube- or cone-shaped fold in strongly deformed rock.
- How it forms
- Formed when rock is intensely sheared and stretched.
Mineral
الأوليفين
- Looks like
- Olive-green glassy grains.
- How it forms
- A main mineral of Earth’s upper mantle.
Mineral
العقيق (الغارنت)
- Looks like
- Deep red, rounded crystals.
- How it forms
- Grows in rocks under high pressure and temperature.
Mineral
الكالسيت
- 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.
تعلّم في الميدان
انقل الدرس إلى الهواء الطلق مع GeoAstro Oman
برنامج الجيولوجيا للمدارس
تحضير في الفصل، ورحلة ميدانية مُرشدة، وأنشطة متابعة لطلابك.
احجز برنامج الجيولوجيا للمدارسطلب حجز عبر واتساب (يفتح واتساب في نافذة جديدة)جولة جيولوجيا مسقط
سبع محطات من الأفيوليت إلى إكلوجيت السيفة.
احجز جولة جيولوجيا مسقططلب حجز عبر واتساب (يفتح واتساب في نافذة جديدة)جولة جيولوجيا الجبل الأخضر
خمس محطات من حديقة المرجان إلى الرحلة الثقافية في قرية العين.
احجز جولة جيولوجيا الجبل الأخضرطلب حجز عبر واتساب (يفتح واتساب في نافذة جديدة)تجربة ميدانية للجامعات
الوصف الميداني والتراكيب والمراجع المنشورة في جبال عُمان.
اطلب تجربة ميدانية للجامعةطلب حجز عبر واتساب (يفتح واتساب في نافذة جديدة)
رسالة واتساب هي استفسار وليست حجزًا مؤكدًا. سيردّ فريقنا لتأكيد التوفر والتفاصيل والبرنامج. تعتمد التجارب على حالة السماء والطقس.