@article{oai:kanazawa-u.repo.nii.ac.jp:00055390,
 author = {Tazaki, Kazue and Takehara, Teruaki and Hashida, Yumiko and Hashida, Shozo and Nakamura, Keiichi and Yokoyama, Akihiko and Aoki, Conami and Tazaki, Fumie and 田崎, 和江 and 竹原, 照明 and 橋田, 由美子 and 橋田, 省三 and 中村, 圭一 and 横山, 明彦 and 青木, 小波 and 田崎, 史江},
 issue = {3},
 journal = {地球科学, Earth Science},
 month = {Jul},
 note = {黒柿はカキノキ科の一つであり，幹・枝・根の断面に黒色の部分があり，心材や辺材には縞が美しい孔雀の羽根のような模様（孔雀杢 くじゃくもく）がある．孔雀杢は何百年と樹齢を重ね，かつ，様々な条件を満たした柿の木だけが黒と白の美しい模様を持つようになった希少な銘木である．材質が竪硬で粘りもあり，細かい細工をする指物に適しており和家具，茶道具などが金沢伝統工芸品となっている．しかし，江戸時代に加賀藩が黒柿の栽培を行っていたとされるものの，その科学的な記録はない．なぜ柿の木の幹に黒い色の美しい模様ができるのかを究明するために，石川県金沢市内に生育している黒柿を採取して，IP，XRD，ICP-MS，XRF，SEM-EDS，放射能測定器を用いて物理化学的，鉱物学的，微生物学的特徴を調べた．本研究試料の「黒柿」のXRD 分析では，セルロースの他に低温型α- クリストバライト，生体アパタイト（燐灰石），ハロイサイトなどの粘土鉱物が含まれていた．黒柿の黒色化した幹に形成する孔雀杢は“珪化木”ということができる．本研究結果から，①黒柿が“珪化木”になるには，まず，根の中心の白色部に認められた微生物がCa >>> P，S >> Mg > Si，Fe，Cl，K，Mn を取り込み，生体アパタイトを形成する．②成長するにしたがって，放射能核種やB，Br を伴って, さらにCa，P，S >> K，Mg，Si，Sr > Cl，Mn，Fe などの元素を取り込みながら黒色化する．③そして，年月を経るにしたがって, 幹の辺材部に黒色の縞模様（孔雀杢）を作りながら低温型α- クリストバライト（珪化木）を形成することが明らかになった．, Kurogaki (Black persimmon; Diospyros kaki) grows very slowly and has extremely hard wood known for its striking black coloration, referred to as the “peacock pattern”. It was formerly planted in Kanazawa, Ishikawa, Japan. Kurogaki is currently very rare, found in only one of every 1,000 to 10,000 trees. Therefore, scientific data on Kurogaki are currently very limited but these trees are highly valuable for manufacturing furniture, tea ceremony goods, boxes, and other miscellaneous articles.
Here we report the characterization of Kurogaki at Kanazawa, Ishikawa, Japan, based on radioactivity, purple mineral light, and H2 O2 reactions in the field. To date, no report has described the results of electron microscopy observations and chemical analyses, which could elucidate simple identification of species. Here we studied the microstructure, mineralogy, chemical composition, and radioactivity associated with microorganisms in Kurogaki wood using analytical data based on X-ray diffraction (XRD), X-ray fluorescence (XRF), inductively coupled plasma-mass spectrometry (ICP-MS), imaging plate (IP), scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS), and semiconductor detectors. We investigated the distribution, location, identification, structure, and differentiation of the black “peacock pattern” parts and ordinarily colored wooden parts and roots.
We evaluated the mineralogy, chemistry, and micromorphology of Kurogaki using a combination of micro techniques. Using XRD, the black “peacock pattern” parts were found to mainly comprise cellulose associated with spherical and beaded microorganisms, mineralized living apatite, α-cristobalite, and halloysite. Particular elements associated with microorganisms were identified using SEM-EDS, which revealed the elemental content maps of the central white spot in cross sections of the “peacock pattern”, indicating high concentrations of Ca, P and S. The chemical compositions of the black and white parts were determined based on mineralogical and chemical data obtained using XRF analyzer and ICP-MS.
Furthermore, we used imaging plate methods to obtain radioactive images of the cross sections of the “peacock pattern”. The objective was to illustrate the association of minerals with various microorganisms that are capable of absorbing both radionuclides and stable isotopes from soil and water. A radio dosage analysis of the higher black parts was performed by imaging plate pictures. We investigated the quantitative radiation dosages of the “peacock pattern” using Ge and Si semiconductor detectors, which revealed 137Cs concentrations.
The black “peacock pattern” parts were richer in almost all elements such as K, Ca, Mg, S, Al, Fe, P, Na, Mn, B and Ba, than the white cellulose parts, indicating a role of microorganisms in mediating the transfer of metal solutes from the hydrosphere and soils. Using SEM-EDS micromorphology, the chemical composition of the black “peacock pattern” parts was found to be associated with α-cristobalite and living apatite having wooden clapper-like microcrystals. The distribution of elements indicated the influences of soils in their surrounding environment. Our results provide the evidence of the ability of microorganisms to immobilize radionuclides in the soils. The microorganisms grow in the black “peacock pattern” parts of Kurogaki.
In conclusion, α-cristobalite and living apatite crystals physically and biologically grow in the sap with cellulose under neutral conditions (pH7) in association with microorganisms using carbon dioxide supplied by bacteria. Therefore, the crystals produced the “peacock pattern” in Kurogaki were formed at late times during the year., 金沢大学理工研究域地球社会基盤学系},
 pages = {97--113},
 title = {希少銘木「黒柿」の物理化学的特徴と生体鉱物化作用},
 volume = {71},
 year = {2017}
}