1:45 PM - 3:15 PM
[O08-P30] Research on weathering of Tago stone.
Keywords:Tago stone, Weathering, Yoshii town, Mineral, Monument of Tago, Ushibuse sandstone
Research on weathering of Tago stone
*Kyogo Ito¹, *Takumi Yoshida¹, *Shinnosuke Shirakura¹
1.Maebashi Higashi High School
1 Background and Objectives of the Research
The text discusses Tago stone, a type of Ushibuse sandstone from Yoshii Town in Gunma Prefecture, Japan, known for its historical significance and diverse uses. Despite the availability of more durable materials, there's a continued preference for Tago stone, especially among local residents who show attachment to it. However, Tago stone is no longer being quarried or sold. Therefore, a research project aims to study Tago stone weathering through field surveys and experiments to aid in its preservation.
2 Research Methods
2-1 Field Survey
We conducted on-site investigations in the vicinity of Yoshii town, Takasaki City, to examine the use of Tago stone in cemeteries and temples. The research parameters included location, purpose, lithology, age, and evaluation of cracks and abrasion on a scale of 1 to 4, with higher numbers indicating more severe damage. The survey was carried out in the fiscal years 2021 and 2022.
2-2 Weathering Experiments
Based on an interview conducted during a visit to Takako Sangyo Co., Ltd., where it was mentioned that Tago stone's weathering is significantly influenced by exposure to water and temperature fluctuations, weathering experiments focusing on temperature and water were conducted twice, in the fiscal years 2022 and 2023.
3 Results
3-1 Field Survey
We surveyed a total of 370 items, including those whose eras were unknown. The results of the extent of reduction are as shown in Table 1. The total count for category 1 was the highest, with the 1600s and 1700s having the second highest count for category 2. For other eras, the count for category 1 was the highest.From Table 2, it can be observed that, similar to Table 1, the count for category 1 was the highest across all eras, with category 1 being the most prevalent.According to Table 3, the majority of the rock compositions were composed of sand.Table 4 indicates that over half of the stones were used for gravestones, and it was also noted that easily weathered Tago stone were used for pillars and foundation stones.
3-2 Weathering Experiments
3-2-1 Results for the Fiscal Year 2022
In the fiscal year 2022, weathering experiments were conducted with items ① to ⑥ as shown in Figure 2. Rocks subjected to repeated cycles of freezing and thawing, such as item ④, exhibited angular shapes similar to those depicted in Figure 3, while rocks left submerged in water, such as item ⑤, developed moss growth, as shown in Figure 4.
3-2-2 Results for the Fiscal Year 2023
In the fiscal year 2023, weathering experiments were conducted with items ① to ⑥ as listed in Table 5. Thin sections were prepared for each tuff stone used in the experiments, as depicted in Figure 5. These sections were then observed under a polarizing microscope to evaluate weathering. Photographs of the thin sections, marked with grids as shown in Figure 6, were taken for each set of five sections. The mineral conditions at the intersections were summarized to assess weathering, categorized into items such as the presence or absence of cracks in colorless minerals, presence of iron hydroxide in colored minerals, and other conditions. The results are presented in Table 5, indicating an increase in iron hydroxide under high-temperature conditions (③) and an increase in cracks in colorless minerals in rocks subjected to repeated cycles of freezing and thawing (④).
4 Discussion
Field surveys show that Tago stones from the same era can differ significantly in abrasion and cracking, suggesting that age alone doesn't determine weathering progression. Limited data hints that Tago stones from the 1600s experienced low abrasion, suggesting the presence of high-quality, weather-resistant stones quarried during that period. Tombstones, being easier to process, exhibit more weathering compared to pillars and lanterns due to their susceptibility to weathering and preservation challenges. Weathering experiments reveal that tuff stones are vulnerable to increased iron hydroxide levels during high temperatures and are prone to weathering from repeated freezing and thawing cycles. This occurs due to faster chemical reactions facilitating greater interaction between iron content in tuff stones and environmental factors like oxygen or water vapor, while freezing and thawing induce weathering by expanding water volume between particles and minerals.
*Kyogo Ito¹, *Takumi Yoshida¹, *Shinnosuke Shirakura¹
1.Maebashi Higashi High School
1 Background and Objectives of the Research
The text discusses Tago stone, a type of Ushibuse sandstone from Yoshii Town in Gunma Prefecture, Japan, known for its historical significance and diverse uses. Despite the availability of more durable materials, there's a continued preference for Tago stone, especially among local residents who show attachment to it. However, Tago stone is no longer being quarried or sold. Therefore, a research project aims to study Tago stone weathering through field surveys and experiments to aid in its preservation.
2 Research Methods
2-1 Field Survey
We conducted on-site investigations in the vicinity of Yoshii town, Takasaki City, to examine the use of Tago stone in cemeteries and temples. The research parameters included location, purpose, lithology, age, and evaluation of cracks and abrasion on a scale of 1 to 4, with higher numbers indicating more severe damage. The survey was carried out in the fiscal years 2021 and 2022.
2-2 Weathering Experiments
Based on an interview conducted during a visit to Takako Sangyo Co., Ltd., where it was mentioned that Tago stone's weathering is significantly influenced by exposure to water and temperature fluctuations, weathering experiments focusing on temperature and water were conducted twice, in the fiscal years 2022 and 2023.
3 Results
3-1 Field Survey
We surveyed a total of 370 items, including those whose eras were unknown. The results of the extent of reduction are as shown in Table 1. The total count for category 1 was the highest, with the 1600s and 1700s having the second highest count for category 2. For other eras, the count for category 1 was the highest.From Table 2, it can be observed that, similar to Table 1, the count for category 1 was the highest across all eras, with category 1 being the most prevalent.According to Table 3, the majority of the rock compositions were composed of sand.Table 4 indicates that over half of the stones were used for gravestones, and it was also noted that easily weathered Tago stone were used for pillars and foundation stones.
3-2 Weathering Experiments
3-2-1 Results for the Fiscal Year 2022
In the fiscal year 2022, weathering experiments were conducted with items ① to ⑥ as shown in Figure 2. Rocks subjected to repeated cycles of freezing and thawing, such as item ④, exhibited angular shapes similar to those depicted in Figure 3, while rocks left submerged in water, such as item ⑤, developed moss growth, as shown in Figure 4.
3-2-2 Results for the Fiscal Year 2023
In the fiscal year 2023, weathering experiments were conducted with items ① to ⑥ as listed in Table 5. Thin sections were prepared for each tuff stone used in the experiments, as depicted in Figure 5. These sections were then observed under a polarizing microscope to evaluate weathering. Photographs of the thin sections, marked with grids as shown in Figure 6, were taken for each set of five sections. The mineral conditions at the intersections were summarized to assess weathering, categorized into items such as the presence or absence of cracks in colorless minerals, presence of iron hydroxide in colored minerals, and other conditions. The results are presented in Table 5, indicating an increase in iron hydroxide under high-temperature conditions (③) and an increase in cracks in colorless minerals in rocks subjected to repeated cycles of freezing and thawing (④).
4 Discussion
Field surveys show that Tago stones from the same era can differ significantly in abrasion and cracking, suggesting that age alone doesn't determine weathering progression. Limited data hints that Tago stones from the 1600s experienced low abrasion, suggesting the presence of high-quality, weather-resistant stones quarried during that period. Tombstones, being easier to process, exhibit more weathering compared to pillars and lanterns due to their susceptibility to weathering and preservation challenges. Weathering experiments reveal that tuff stones are vulnerable to increased iron hydroxide levels during high temperatures and are prone to weathering from repeated freezing and thawing cycles. This occurs due to faster chemical reactions facilitating greater interaction between iron content in tuff stones and environmental factors like oxygen or water vapor, while freezing and thawing induce weathering by expanding water volume between particles and minerals.