Blue stone stupa

…About 30,000 stone monuments are known in the Kanto region, and are made of bluestone (chlorite schist) from Chichibu. Taking advantage of the stone's characteristics of being easy to cut into thin plates and work with, they have triangular heads, two grooved lines, and the main Buddha is expressed with Sanskrit characters or images, and many of them are beautiful in appearance and color, which is why they have been popular with literati since the Edo period. The name "itabi" (slab monument) is most appropriate for these stone monuments in the Kanto region (also called Musashi-gata itabi or blue stone stupas), and in the Tohoku region, there are some that are simply round natural stones with the seed of Buddha and an inscription engraved on them. The faith that went into erecting the stone monuments can be known from the main deity on the stone monument or a verse (ge) from the sutra engraved on the inscription, but the majority express faith in Amida Buddha (more than 80% of Musashi-gata itabi), and the source of the verse is often taken from the Lotus Sutra or the Three Pure Land Sutras. …

*Some of the terminology that refers to "Blue Stone Stupa" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…関東地方のものは，現在までに約3万基が知られ，秩父産の青石(緑泥片岩)で作られ，薄く板状にはがれやすく加工もしやすい，という石材の特色を生かし，頭部を三角形とし，2本の溝状の線を刻み，梵字や画像で主尊の仏を表現するなど，形態的にすぐれ色も美しいものが多く，そのため，江戸時代から文人などに好まれてきた。板碑という名称もこの関東地方の板碑(武蔵型板碑，青石塔婆などともよばれる)にもっともふさわしいもので，東北地方などには，丸い自然石に仏の種子（しゆじ）と銘文が刻まれるだけのものもある。　板碑造立にこめられた信仰は，板碑の主尊や銘に刻まれた経典の一句(偈（げ）)から知ることができるが，大半は阿弥陀仏に対する信仰(武蔵型板碑では8割以上)を表明し，偈の出典としては，法華経や浄土三部経から引かれることが多い。…

※「青石塔婆」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報