Aji Stone Products are stone products made from Aji stone (Aji-ishi), a granite quarried in Aji-cho and Mure-cho in Takamatsu City, Kagawa Prefecture. Aji stone is quarried at the foot of Mt. Gokenzan and is formally classified as fine-grained biotite granodiorite. Because it is fine-textured and hard, it gains luster the more it is polished and resists discoloration even over the years. Its greatest distinguishing feature is 'fu,' a mottled pattern of biotite that emerges when it is polished, and it is also called 'the diamond of granite.' Because it is also well suited to fine carving, it has long been prized as a material not only for high-end gravestones but also for stone lanterns, stone Buddhist statues and sculptures. It is also known as a stone praised by the sculptor Isamu Noguchi. It is designated a Kagawa Prefecture Designated Traditional Craft under the name 'Aji Production Area Stone Products,' and more than 200 businesses are still gathered in the production area today.
Origin
According to Kagawa Prefecture statistical materials, Aji stone has been quarried since the late Heian period and was shipped as far as Kyoto. Processing it into stone products is said to have begun about 650 years ago. There is also a theory that it began when Toyotomi Hideyoshi sought stone from Sanuki for the construction of Osaka Castle and stone was shipped out from the port of Aji. A 1991 article by the Geological Survey of Japan also noted that there are traces of Aji stone having been used in Osaka Castle and Takamatsu Castle.
History
In the Edo period, the area became a goyo-choba (official quarry) of the Takamatsu domain, and quarrying and processing developed rapidly. When construction of Yashima Toshogu Shrine began in 1814, stonemasons were invited from Izumi Province (present-day Osaka Prefecture) and settled in the area, laying the foundation of the production area. From the Meiji era to the early Showa era, there are said to have been many orders for stone lanterns and stone Buddhist statues. After World War II, mechanization with cutting and polishing machines advanced, and processing changed significantly with the introduction of stone-cutting machines around 1960 (Showa 35).
Features
Aji stone is fine-grained, and its minerals are arranged with almost no directionality, making it easy to carve even fine details. Because carved characters are easy to read and stand out well, it has been especially prized for gravestones. The 'fu' that arises from the uneven distribution of biotite and quartz appears, when polished, like layered kasuri (splashed-pattern weave), and it is highly valued. Depending on the fineness of the grain, there are classifications such as 'komame' (fine grain) and 'nakame' (medium grain).
Materials Used
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Artisans & Workshops
伏石石材（伏石康宏）
A stone shop that processes Aji stone. In a collaboration project between the magazine Katei Gaho and Kagawa Prefecture, 伏石康宏 handled the design and production, and an Aji stone cooler and plate set was announced as a made-to-order item. The price is 90,000 yen (tax included).
Official site →有限会社島本石材工業
A stone-processing business in Mure, Mure-cho, Takamatsu City. A traditional crafts guide issued by Takamatsu City in April 2026 introduced an experience of making an ishi-akari (stone lamp) from Aji stone, with a fee of 3,300 yen and a duration of about 1 hour 30 minutes.
How to Buy
- AJI PROJECT
- A lifestyle goods brand for Aji stone launched in 2012 in partnership with the Takamatsu City Mure-Aji Chamber of Commerce and Industry. It offers chopstick rests, flower vases, cutting boards and other items devised by stonemasons of the production area, with general retail prices mainly ranging from 1,780 yen up into the 10,000-yen range.Where to buy →PR
Hands-on Experiences
高松市石の民俗資料館
香川県高松市牟礼町牟礼1810
Life-size figure dioramas recreate scenes of stone cutting and transport from the late Taisho era to the early Showa era, and about 1,000 stonemason's tools are on display. There are also workshops such as 'Ishi de Paint,' in which visitors paint on stones. Admission is 200 yen for general visitors, and it is closed on Mondays.
イサム・ノグチ庭園美術館
香川県高松市牟礼町牟礼3519
A museum that opens to the public the studio and residence the sculptor Isamu Noguchi established here from 1969, where about 150 sculptures and other works can be seen. Visits are by reservation only, and applications must be made by return postcard (ofuku hagaki). The admission fee for general visitors is about 2,000 to 3,000 yen; since the listed amount differs depending on when it was published, it is recommended to check in advance.
FAQ
Q. What does it mean that the 'fu' emerges?
A. It is a phenomenon in which, when Aji stone is polished, a mottled pattern caused by the uneven distribution of biotite and quartz appears to float up on the surface. It also looks like layered kasuri, and it is highly valued as a characteristic unique to Aji stone.
Q. Why is Aji stone expensive?
A. It is said to be because the quarries (choba) are limited to the area around Mt. Gokenzan and high-quality raw stone is scarce. A 1991 article by the Geological Survey of Japan also explained that top-grade raw stone was running out, the number of quarrying businesses was decreasing, and prices were high. Its fine texture and beauty after polishing also support its reputation.
Q. Where are the Aji stone quarries?
A. The quarries are called 'choba,' and they are concentrated in the area on the western side of Mt. Gokenzan, along the border between Aji-cho and Mure-cho. A 1991 article by the Geological Survey of Japan reported that there were about 60 choba, each quarried by an independent business that sold the raw stone to processors.
Q. How much stonework is produced in Kagawa Prefecture?
A. According to Kagawa Prefecture statistics, the shipment value of stonework products in 2023 (Reiwa 5) was 4.433 billion yen, ranking third in Japan with a 9.6% share. The stone industry of Aji and Mure is one of the prefecture's representative local industries.
Q. Where can I see works of art made with Aji stone?
A. At the Isamu Noguchi Garden Museum in Mure-cho, you can see Noguchi's sculptures (reservation required). In Aji, the studio and residence of the sculptor Nagare Masayuki (1923–2018) is open to the public as 'NAGARE STUDIO.' Stone sculptures are also on display at the Stone Folk Museum.