Dingdaohengite-(Ce)

Chemical formula: (Ce₃+,La₃+)₄Fe₂+(Ti₄+,Fe₂+,Mg,Fe₃+)₂Ti₄+₂Si₄O₂₂

Dingdaohengite-(Ce) is a very rare, black mineral from the tshogmanite group, discovered in China, with a complex chemical composition containing cerium and titanium.

## Characteristics Dingdaohengite-(Ce) is a black mineral with a resinous to metallic luster. It occurs as short, prismatic crystals, typically not exceeding 1 mm in length. These crystals are often grouped into aggregates. It is opaque and exhibits weak pleochroism in shades of brown. ## Physical Properties The mineral is characterized by a Mohs hardness of 6. Its density is relatively high, approximately 4.93 g/cm³. It has a black streak and an uneven fracture. It does not exhibit cleavage. ## History and Name The mineral's name honors Professor Ding Daoheng (1914–2003), a Chinese geologist and mineralogist from the Chinese Academy of Geological Sciences in Beijing, for his contributions to ore deposit research. The suffix "-(Ce)" refers to the dominant rare-earth element in its composition – cerium. The mineral was officially approved by the IMA in 2004, and its description was published in 2006.

Properties

Mohs hardness: 6
Luster: Sub-metallic
Streak: Black
Density: 4.93
Cleavage: None
Fracture: Uneven
Transparency: Opaque
Crystal system: Monoclinic

Diagnostic features

## Identification Field identification is practically impossible due to its rarity and small size. In a collection, it is recognized by its black color, prismatic crystal habit, and association with characteristic minerals from its type locality. Final confirmation requires advanced analytical methods, such as X-ray microanalysis (EDS/WDS). ## Distinguishing from Similar Minerals It can be confused with other black, titanium-bearing minerals, such as ilmenite or other minerals from the tshogmanite group. Differentiation based on visual characteristics is unreliable; key is the determination of cerium presence and specific crystal structure. ## Crystal Forms It forms short, prismatic crystals with a cross-section resembling a square or rectangle. Crystals are typically very small, up to 1 mm in length.

Geological environment

## Genesis Dingdaohengite-(Ce) forms under conditions of high-pressure metamorphism. At its type locality, it was found in quartz veins cutting coesite-quartz gneisses within eclogites. ## Mineral Associations This mineral co-occurs with quartz, rutile, apatite, allanite-(Ce), and other minerals from the tshogmanite group, such as tshogmanite-(Ce). ## Localities The only confirmed occurrence worldwide is its type locality: Hushan in Donghai County, Lianyungang Prefecture, Jiangsu Province, China. This is part of the ultrahigh-pressure (UHP) Sulu metamorphic belt.

Rarity

Extremely rare

For collectors

## Quality Criteria As a "micromount" type mineral, its collector value primarily depends on the quality and size of individual crystals, as well as the richness of the specimen (number of crystals on the matrix). Well-formed, undamaged prismatic crystals, clearly visible against a light quartz matrix, are the most desirable.

Care and storage

## Cleaning Due to its rarity and small crystal size, specimens typically do not require cleaning. If necessary, compressed air can be used to remove dust. Mechanical and ultrasonic cleaning should be avoided. ## What to Avoid Contact with strong acids and chemicals that could damage the mineral's surface should be avoided. There is no detailed data on sensitivity to light or temperature, but standard caution is recommended, as with other rare minerals. ## Storage Specimens should be stored in stable conditions, in dedicated collector boxes (so-called micromounts), to protect them from mechanical damage and dust. Due to the small size of the crystals, microscopic examination is the best way to display them.

Sources

IMA Mineral List (CNMNC)