CT Carbonaceous Chondrites
CT carbonaceous chondrites represent a newly recognized group of primitive carbonaceous meteorites, named after Telakoast 001. This group was proposed following detailed studies of multiple very fine-grained, black and often friable carbonaceous chondrites that had previously been difficult to classify with confidence.
Several CT specimens were formerly regarded as CM2 or anomalous CM chondrites, largely because of their dark appearance and fine-grained texture. However, combined petrographic, mineralogical, magnetic susceptibility and oxygen isotope studies indicate that CT chondrites form a distinct group within the carbonaceous chondrite family.
Recognized CT members include Telakoast 001, Chwichiya 002, Cimarron, and several Northwest African meteorites. Their identification highlights how much remains to be refined in the classification of primitive carbonaceous meteorites.
A Newly Recognized Carbonaceous Group
The CT group was defined through the study of multiple specimens sharing common petrographic and isotopic characteristics. Unlike more familiar groups such as CV, CK, CR and CO chondrites, CT chondrites are generally much finer grained and more difficult to classify by visual inspection alone.
According to the reference study, CT chondrites consist of small chondrules with a mean apparent diameter of about 280 µm, set within very fine-grained matrices. This fine texture helps explain why some specimens were previously mistaken for CM-like material.
Petrography and Mineralogy
CT chondrites display small chondrules embedded in a fine-grained matrix, with olivine compositions covering a wide range. Accessory phases reported in CT specimens include:
- Kamacite
- Pyrrhotite
- Pentlandite
- Chromite
- Magnetite
- Maghemite
- Taenite
- Calcite
- Dolomite
The study also notes that tochilinite is absent and that no calcium-aluminum-rich inclusions were observed in the examined CT specimens. Minor serpentine and smectite were detected only in some CT2 specimens, including NWA 11699 and Sarir Tazirbu 001.
Oxygen Isotopes and Classification
Oxygen isotope analyses are essential for recognizing CT chondrites. The reference study shows that CT specimens define a distinct linear array in oxygen isotope space, displaced from the arrays of CV, CO, CK and CL chondrites.
This isotopic distinction is one of the strongest arguments for treating CT chondrites as a separate carbonaceous chondrite group rather than as unusual CM chondrites.
Known CT Chondrites
The CT group includes both CT3 and CT2 specimens. Reported CT3 members include:
- Telakoast 001
- Cimarron
- Chwichiya 002
- NWA 6862
- NWA 8781
- NWA 12416
- NWA 12957
- NWA 13671
- NWA 13984
- NWA 14051
- NWA 14139
- NWA 14179
- NWA 14200
Reported CT2 members include:
- NWA 11699
- Sarir Tazirbu 001
- Oued Mya 002
Scientific Importance
CT chondrites are scientifically important because they demonstrate that some fine-grained carbonaceous chondrites previously assigned to familiar groups may require reassessment using modern analytical methods.
Their recognition emphasizes the importance of:
- Oxygen isotope analysis
- Petrographic study
- Magnetic susceptibility measurements
- X-ray diffraction analyses
- Careful comparison with CM, CI, CY and other carbonaceous groups
Because CT chondrites are newly recognized, they are of particular interest to researchers and advanced collectors focused on primitive Solar System materials and evolving meteorite classification.
Appearance and Collector Interest
CT carbonaceous chondrites are typically dark, fine grained, and visually subtle compared with CAI-rich CV chondrites or metal-rich CR and CB chondrites.
Their appeal lies primarily in their scientific rarity and classification significance rather than dramatic visual texture. Collectors particularly value:
- Confirmed CT classification
- Fresh fusion crust
- Low terrestrial weathering
- Documented oxygen isotope data
- Material from recognized CT members
- Research-grade fragments or slices
Authentic CT Carbonaceous Chondrites
Authentic CT carbonaceous chondrites are rare and highly specialized specimens. Because this group is recently recognized, well-documented material with reliable classification data is especially important.
Each CT specimen represents part of a developing chapter in carbonaceous chondrite classification and contributes to a more refined understanding of primitive asteroid materials.
