1:45 PM - 3:15 PM
[O11-P69] Discussion of Quartz and Allanite found in the area of Daibosatsu Ridge - Daibosatsu Pass, Yamanashi Prefecture, Japan
Keywords:Daibosatsu Pass, Allanite, metamictizaiton
In 2023 and 2024, I visited the Daibosatsu Ridge, which stretches from Koshu City to Tambayama Village in Yamanashi Prefecture, four times: twice as part of the science observation camp of my science club and twice as part of the “Daibosatsu Geotour” organized by the alumni association of the mountain club of Musashi High School and ‘Geotrekademie’. On those occasions, I obtained information on the Internet that there was a locality of Allaniate near the place where I stayed, so I searched for the locality and found it, relying on the information provided. We found quartz veins along the hollowed terrain like a dry stream, and rarely we could find rocks with Allanite. Those in rock and those with quartz were found with equal frequency, and those in rock were confirmed by the discoloration of the rock around the Allanite. Since Allanite contains radioactive elements and concentric stain-like radioactive halos are sometimes observed, we concluded that this mineral is definitely Allanite. Some columnar crystals could be observed as the figure, and some crystals were observed that appeared to have been metamictized and the crystals destroyed.
Allanite is a member of the greenstone family and is a silicate mineral that contains many rare earth elements such as Ce and Y. Its English name is allanite. Although it contains many elements, it is thought that the Ca2+ in Clinozoisite is substituted for rare earths such as La3+ and Ce3+, and the Al3+ is highly substituted for Fe2+ and Mn2+. The cleavage of brownstones is complete in one direction, but often no cleavage is observed due to the presence of radioactive elements such as U and Th, which destroy the crystal structure (metamictization). The color is brown to black, glassy, opaque, and submetallic. Striations are brown to black, with a Mohs hardness of 5.5 and a specific gravity of 3.3 to 4.2. It is widely found in granite in small quantities. The main sources in Japan are the granite pegmatites of Mt. In particular, the Daimonjiyama brownstone was the first to be discovered in Japan and is listed in the Kyoto Prefecture Red Data Book, which was also used as a reference in writing this document.
The source of the Allanite is considered to be pegmatite derived from granite that was intruded during the Miocene Eocene of the Cenozoic Era. The western part of the area is made up of the Kofu Body, which is composed of the granite, and the eastern part is made up of an accretionary body called the Shimanto Body. The outcrops seen on the way up the trail from the production area are sandstone beds, and according to the AIST Seamless Geological Map, the geology near the production area is also sandstone beds, suggesting that the granite pegmatite is partially exposed.
In addition, since what we currently know is limited to what is described in the literature and what we have read by observing the sample, we would like to conduct a more detailed analysis using the sample before the day of JpGu2025. Specifically, we are considering whether there is any difference in radiation levels between the metamictized and non-metamictized portions by measuring radiation levels using a Geiger counter, and whether thorium can be confirmed using a colorimetric method. In addition, we would like to actually read and refer to the the book “Japanese Rare Element Minerals” written by father and son Otokichi and Kozo Nagashima, because the Internet page and the literature where we obtained information on the locality we referred to said that information on Allanite is described in that book.
On the day of the presentation at the JpGU 2025 high school students' session, one of the objectives is to deepen their interest in minerals, rocks, and related geology through conveying information about Allanite based on collected samples and literature, and ultimately to convey the appeal of geoscience.
Allanite is a member of the greenstone family and is a silicate mineral that contains many rare earth elements such as Ce and Y. Its English name is allanite. Although it contains many elements, it is thought that the Ca2+ in Clinozoisite is substituted for rare earths such as La3+ and Ce3+, and the Al3+ is highly substituted for Fe2+ and Mn2+. The cleavage of brownstones is complete in one direction, but often no cleavage is observed due to the presence of radioactive elements such as U and Th, which destroy the crystal structure (metamictization). The color is brown to black, glassy, opaque, and submetallic. Striations are brown to black, with a Mohs hardness of 5.5 and a specific gravity of 3.3 to 4.2. It is widely found in granite in small quantities. The main sources in Japan are the granite pegmatites of Mt. In particular, the Daimonjiyama brownstone was the first to be discovered in Japan and is listed in the Kyoto Prefecture Red Data Book, which was also used as a reference in writing this document.
The source of the Allanite is considered to be pegmatite derived from granite that was intruded during the Miocene Eocene of the Cenozoic Era. The western part of the area is made up of the Kofu Body, which is composed of the granite, and the eastern part is made up of an accretionary body called the Shimanto Body. The outcrops seen on the way up the trail from the production area are sandstone beds, and according to the AIST Seamless Geological Map, the geology near the production area is also sandstone beds, suggesting that the granite pegmatite is partially exposed.
In addition, since what we currently know is limited to what is described in the literature and what we have read by observing the sample, we would like to conduct a more detailed analysis using the sample before the day of JpGu2025. Specifically, we are considering whether there is any difference in radiation levels between the metamictized and non-metamictized portions by measuring radiation levels using a Geiger counter, and whether thorium can be confirmed using a colorimetric method. In addition, we would like to actually read and refer to the the book “Japanese Rare Element Minerals” written by father and son Otokichi and Kozo Nagashima, because the Internet page and the literature where we obtained information on the locality we referred to said that information on Allanite is described in that book.
On the day of the presentation at the JpGU 2025 high school students' session, one of the objectives is to deepen their interest in minerals, rocks, and related geology through conveying information about Allanite based on collected samples and literature, and ultimately to convey the appeal of geoscience.