Stones of Türkiye: from Oltu stone and boron to Cappadocian tuff and Kula

Türkiye’s stones stand out worldwide in several ways. According to Eti Maden, about 73% of the world’s boron reserves are in Türkiye, and according to the U.S. Geological Survey (USGS), Türkiye is the world’s second-largest producer of chromite. Oltu stone from Erzurum, meerschaum from Eskişehir and colour-change diaspore (zultanite) from Muğla are the ornamental stones that have made the country known abroad, while Afyon marble, Denizli travertine, Cappadocian tuff and Ahlat stone have been used as building stones for thousands of years.

This article introduces Türkiye’s most notable stones, where they are found and where you can see them.

At a glance

Stone	Where?	Why it matters
Oltu stone	Oltu, Erzurum	Organic stone, a kind of jet; geographical indication
Meerschaum	Eskişehir	Sepiolite carved into pipes and ornaments; geographical indication
Zultanite (diaspore)	İlbir Mountains, Milas, Muğla	Main known source of gem-quality colour-change diaspore
Boron minerals	Kırka, Emet, Bigadiç	Most of the world’s reserves
Chromite	Elazığ (Guleman), Muğla and other ophiolite areas	World’s second-largest producer
Marble	Marmara Island, Afyonkarahisar and elsewhere	Famous quarries since antiquity
Travertine	Denizli, Pamukkale	Building stone with a designation of origin; UNESCO site
Tuff and ignimbrite	Cappadocia, Ahlat	Fairy chimneys and Seljuk gravestones
Basalt	Kula, Manisa	UNESCO Global Geopark

Ornamental stones linked with Türkiye

Oltu stone

Mined from small galleries in the Oltu district of Erzurum, Oltu stone is an organic stone formed from coalified wood; mineralogists know it as jet. According to its geographical indication certificate, it is about 78% carbon, surprisingly light in the hand, becomes charged by friction and attracts light objects, and leaves a brown powder when rubbed on sandpaper. It is soft when it comes out of the ground and hardens as it is exposed to air. The name “Oltu Taşı” has been protected by a geographical indication since 2012. How to tell it from imitations is explained in our fake gemstones guide.

Meerschaum

Meerschaum, the mineral sepiolite, is a white, light and porous clay mineral. Because it is soft and easy to carve, it is used above all for pipes and ornaments. Eskişehir is famous for its meerschaum deposits, and “Eskişehir Lületaşı” (Eskişehir meerschaum) has been a registered geographical indication since 1999.

Zultanite: colour-change diaspore

In the İlbir Mountains near Milas in Muğla province, transparent, gem-quality diaspore crystals occur in bauxite deposits. The stone is sold under trade names such as zultanite and csarite. Its most striking feature is a change of colour: the same stone looks greenish or pinkish-orange depending on the light source. The İlbir Mountains are the main known source of this gem-quality diaspore.

Minerals: boron and chromium

Boron

Boron minerals are used mostly in the glass and ceramics industries, and also in everything from cleaning products and insulation to semiconductor manufacturing. According to Eti Maden, Türkiye holds about 73% of the world’s boron reserves. The USGS 2026 report also lists the largest reserves for Türkiye, while noting that a world total cannot be calculated because countries report their data in different ways. According to the same report, 90% of the boron the United States imported in 2021–2024 came from Türkiye.

The main deposits are:

• Kırka (Eskişehir): Borax (tincal). According to Eti Maden, the Kırka-Sarıkaya formation has the largest share of the world’s tincal reserves.
• Emet (Kütahya): Colemanite. According to the USGS, about 70% of Türkiye’s boron deposits are colemanite.
• Bigadiç (Balıkesir): Colemanite and ulexite.

Chromium

Chromium is an essential ingredient of stainless steel and is obtained from the mineral chromite. According to the USGS 2026 report, Türkiye is the world’s second-largest producer of chromite after South Africa. Türkiye’s chromite deposits usually occur as lens-shaped bodies in ophiolites, slices of ancient ocean floor thrust onto land; the Guleman area in Elazığ and the Köyceğiz-Fethiye area in Muğla are well-known examples.

Building stones that shaped history

Marble: Marmara and Afyon

The Sea of Marmara takes its name from the marble quarries of Marmara Island. The grey-veined white marble of the island, known in antiquity as Proconnesus, was shipped all over the Mediterranean in Roman and Byzantine times and used in buildings such as Hagia Sophia. The İscehisar district of Afyonkarahisar is the site of ancient Docimium; the white marble with purple veins quarried there (pavonazzetto) was used in the buildings of Roman emperors such as Augustus, Trajan and Hadrian. İscehisar is still known today for its marble quarries and factories.

Denizli travertine and Pamukkale

Travertine is a porous limestone deposited by hot springs rich in calcium carbonate. The brilliant white terraces of Pamukkale are a place where this process is still going on, and together with the ancient city of Hierapolis they have been on the UNESCO World Heritage List since 1988. Stone quarried from Denizli’s travertine basins is registered as a designation of origin under the name “Denizli Traverteni” and is used for building and cladding.

Cappadocian tuff

Cappadocia’s fairy chimneys formed as wind and water eroded layers of volcanic ash, that is tuff and ignimbrite, left by eruptions of volcanoes such as Erciyes and Hasan millions of years ago. Because the rock is soft and easy to carve, churches, homes and underground cities were dug into it. “Göreme National Park and the Rock Sites of Cappadocia” has been on the UNESCO World Heritage List since 1985. You can read how such rocks form in our rock cycle article.

Ahlat stone

The volcanic rock known locally as “Ahlat stone” in Ahlat, on the shore of Lake Van, is an ignimbrite. Easy to work, it was used for the carved gravestones of the Ahlat Seljuk Cemetery, which is on UNESCO’s World Heritage Tentative List. Today scientists study how lichens and moisture are wearing these gravestones away.

Volcanoes and geoparks: Kula

The area around Kula in Manisa province is a geologically very young volcanic field: about 80 scoria cones and dark basalt lava flows lie side by side. In antiquity the region was called Katakekaumene, the “burnt land”; the geographer Strabo was the first to describe this volcanic belt. The Kula area joined the European and Global Geoparks Networks in 2013, becoming Türkiye’s first geopark, and today it is the Kula-Salihli UNESCO Global Geopark. Geoparks are areas where geological heritage is managed together with education and sustainable tourism.

Where can you see Türkiye’s stones?

• MTA Şehit Cuma Dağ Natural History Museum (Ankara): Run by the General Directorate of Mineral Research and Exploration (MTA), the museum opened in 1968 and displays more than 5,000 specimens: minerals, rocks, fossils and meteorites from Türkiye and around the world. The museum’s gemmology laboratory also examines stones for the public; see Is my stone valuable? for details.
• On site: At Pamukkale, in Cappadocia, in the Kula-Salihli Geopark and in Ahlat you can see the stones in their natural setting or in historic buildings.

When you travel, remember that taking stones from protected areas, archaeological sites and shores is prohibited or requires permission. For details, see Is collecting stones legal?