Baotite

The mineral Baotit (Chinese包头 矿, Pinyin Baotoukuang ) is a rare ring silicate mineral from the class of silicates. It crystallizes in the tetragonal crystal system with the chemical composition Ba4 (Ti, Nb) 8Si4O28Cl, and develops predominantly light brown and black crystals with a size of up to ten centimeters.

Special Features

The mineral is optically uniaxial with the refractive indices nw = 2.16 and nε = 1.94; the birefringence δ is 0.220. It is strongly pleochroic from colorless and pale greenish yellow.

Etymology and history

Peng Qirui彭琪瑞(1917-1985) in 1959 in the Scientia Geologica Sinica journal ( Dizhi Kexue ) first published on Baotit. The mineral was discovered in the Bayan Obo mine, on the territory of the municipality Shiguai ( Xiguit ), the prefecture-level city of Baotou in Inner Mongolia, People's Republic of China.

Classification

Baotit belongs to the class of ring silicates in the group of [ Si4O12 ] 8- foursome - Simple rings without insular complex anions.

Education and Locations

In Bayan Obo the mineral comes in Proterozoic rocks in quartz veins with galena and pyrite ago. The quartz veins are due to the intrusion variskischer alkali granites and syenites.

In addition to the type locality in Bayan Obo another location from the San Benito County in California is given. Finds of Baotit have also become known from Pakistan, Czech Republic, Canada, New Zealand, Russia and Tajikistan.

Crystal structure

Baotit crystallizes in the tetragonal crystal system, space group I41 / a with lattice parameters a = 20.02 Å and c = 6.0 Å and 16 formula units per unit cell.