• Title/Summary/Keyword: 흑요석

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Morphology and Texture of Microlites in the Baekdusan and Kyushu Obsidians (백두산과 규슈 흑요석 내 미세결정의 형태와 조직)

  • Hwang, Ga-hyun;Jwa, Yong-Joo
    • Journal of the Korean earth science society
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    • v.38 no.7
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    • pp.546-551
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    • 2017
  • We examine the morphology and texture of microlites included in the obsidians from the Baekdusan (Mt. Baekdu) and Kyushu (SW Japan) by using an electron microscope. According to the morphological types of microlites, the microlites in the Baekdusan obsidians are classified as Arculites, Asteroidal and Crenulite, whereas those in the Kyushu obsidians as various types of Arculites, Bacillite, Belonites, Crenulite, Furculite, Lath, Margarite, and Scopulites. Specifically, the Arculites in both obsidians show very distinctive crystal relationships, though they are mainly composed of magnetite and pyroxene. The Baekdusan Arculites exhibit the poikilitic texture of pyroxene crystals enclosing multiple magnetite crystals, whereas the Kyushu ones demonstrate the granular and/or intergranular texture of interlocking between magnetite and pyroxene crystals. This distinction can be used to discriminate the provenance of the obsidian artefacts from the prehistoric sites in the Korean Peninsula.

Mineralogical Study on Microlites in the Baekdusan Obsidian and the Gadeokdo Obsidian Artefacts (백두산 흑요석과 가덕도 흑요석제 석기에 포함된 미세결정에 대한 광물학적 연구)

  • Jin, Mi Eun;Moon, Sung Woo;Ryu, Choon Kil;Jwa, Yong-Joo
    • Journal of the Mineralogical Society of Korea
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    • v.27 no.4
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    • pp.243-249
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    • 2014
  • We conducted investigations into the morphological characterstics and chemical compositions of the microlites included in the obsidians from the North Korean side Baekdusan (NK) and in the obsidian artefacts from the Busan Gadeokdo prehistoric site (BG). The morphology of the microlites from the NK can be divided into three groups, and trichite-acicular and trichite-asteroidal types are predominant. On the other hand the microlites from the BG show various morphological features such as acicular, margarite, lath, and asteroidal types. Silicate microlites from the NK are mostly of Ca-pyroxene compositions (hedenbergite to augite), whereas those from the BG are mostly of biotite (annite) with small amount of clinopyroxene (ferrosilite). It is well understood that the microlites from the NK are different from those from the BG in terms of the morphology, mineral content and mineral composition. Thus the obsidian aretefacts from the Busan Gadeokdo prehistoric site seem to have no genetical relationship to the obsidians from the Baekdusan.

Petrologic and Mineralogic Studies on the Origin of Paleolithic Obsidian Implements from Wolseongdong, Korea (월성동 구석기 유적 출토 흑요석제 석기의 암석 및 광물학적 연구를 통한 원산지 추정)

  • Jang, Yun-Deuk;Park, Tae-Yoon;Lee, Sang-Mok;Kim, Jeong-Jin
    • Journal of the Korean earth science society
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    • v.28 no.6
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    • pp.733-742
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    • 2007
  • Petrological, mineralogical, and geochemical analyses were carried on the paleolithic obsidian implements excavated at Wolseongdong, Daegu, Korea. The obsidians has a homogeneous glassy texture that can be observed in a typical obsidian formed from a rapid cooling of silicic magma. Major element composition of the obsidians represent calc-alkaline series. Comparing those with other obsidians from domestic local excavation sites, Mt. Baekdu, and Kyusu of Japan, the Wolseongdong obsidians show similar element distribution pattern with others in spite of small difference in trace and rare Earth element contents. Sr isotopes of the obsidians considerably differ from those of the obsidians from southern part of the Korean Peninsula or from Mt. Baekdu. K-Ar age is approximately 30 Ma, which is much older than Mt. Baekdu (10 Ma). Therefore, considering the characteristics of obsidians found in the Korean Peninsula including mineralogy, petrology, trace element, and isotopes chronology, the obsidians can be divided into four groups: Mt. Baekdu, southern part of Korea (Kyusu of Japan), middle part of Korea, and Wolseongdong region. These groups suggest a possibility of more than four different origins of the obsidians found in the Korean Peninsular.

Gemological Comparison between Gwangdong Tektite and Baikdusan Obsidian (텍타이트와 흑요석의 보석학적 특징비교 - 중국 광동 텍타이트와 백두산 흑요석을 중심으로 -)

  • Kim, Won-Sa
    • Journal of the Mineralogical Society of Korea
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    • v.20 no.3
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    • pp.181-191
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    • 2007
  • The gemological charateristics of Gwangdong tektites and Baikdusan obsidians were investigated, using microscopy, density and refractive index measurements, X-ray fluorescence spectrometry, Inductively Coupled Plasma Mass spectrometry, X-ray powder diffraction, and electron microprobe analysis. The Gwangdong tektites and Baikdusan obsidians are both black in colour and slightly trans-lucent with various shades of brown when cut into a few mm thick. Both the materials yield conchoidal fracture on broken surface. The tektites occur as tear-drop shapes, ranging from 4 to 10 cm long, and in spheres, from 3 to 5 cm in diameter. On the surface numerous shallow pits up to 3 mm in diameter are present. Mohs' hardness and specific gravity are 5 to 5.5 and 2.66, respectively. The tektites are singly refractive, with an refractive index of 1.51. Numerous spherical air bubbles are randomly scattered throughout the tektites, and silica-rich glass inclusions are occasionally seen. X-ray powder diffraction analysis verifies that they are non-crystalline. The Baikdusan obsidians show very similar properties to those of the Gwangdong tektites, especially in hardness, amorphous nature and fracture. Nevertheless, the Baikdusan obsidian can readily be distinguished from the Gwangdong tektites by refractive index ($1.49{\sim}1.50$), specific gravity (2.67 to 2.68), and inclusions (absence of bubbles and presence of sanidine and magnetite crystals).

Classification of Obsidian Artifacts found in the Korean Peninsula by Chemical Compositions and Magnetic Properties (성분분석 및 자기적 특성에 의한 한반도 흑요석의 분류 연구)

  • Cho, Nam-Chul;Park, Yong-Hee;Doh, Seong-Jae;Kang, Hyung-Tae;Nam, In-Tak
    • Journal of Conservation Science
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    • v.16 s.16
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    • pp.89-103
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    • 2004
  • Provenance discrimination of sixty four obsidian artifacts found in the Korean Peninsular has been carried out using major elements, minor elements and magnetic properties. Most of obsidians in this study were classified into the subalkaline series based on the contents of $Al_2O_3,\;CaO,\;and\;Na_2O+K_2O$ in samples. Provenance & obsidians were classified into three major groups using major elements and minor elements analyse. This result suggests that there are no correlations among the three groups whose provenances are different. Although the magnetic properties of obsidians do not yield clear groupings according to the archaeological site, the bivariate plot for the magnetic susceptibility and the saturation isothermal remanent magnetization shows a rough correlation with the results of major and minor elements analyses.

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Detailed Morphology and Texture of Microlites in Obsidian observed through Electron Microscopy (전자현미경을 이용한 흑요석 내 미세결정의 형태와 조직 관찰)

  • Jwa, Yong-Joo;Hwang, Ga-hyun
    • Journal of the Korean earth science society
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    • v.39 no.6
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    • pp.568-574
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    • 2018
  • Microlite is crystallized under the supercooled condition of volcanic magma. This study reports the morphology and texture of microlites included in the obsidians from the Baekdusan (Mt. Baekdu), Kyushu (Japan), Hokkaido (Japan) and Lipari Island (Italy) by using a scanning electron microscope (SEM). Morphology and texture observed from the back scattered electron (BSE) image could give more detailed information on the microlite crystallization which cannot be acquired from the conventional optical microscope. Ten types of microlites are newly described according to the 14 morphological types of microlites by Clark (1961): Lath, Crenulite, Bacillite, Margarite, Belonites, Trichites, Arculites, Furculite, Scopulites, Scopulitic growth. Detailed description of the ten microlites can be used to interpret the crystallization and paragenetic relations of crystals during the cooling of acidic volcanic magma.

지질과학의 세계 - 이집트선 5천년 전 뇌수술도

  • Jang, Sun-Geun
    • The Science & Technology
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    • v.33 no.10 s.377
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    • pp.13-13
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    • 2000
  • 우리는 인류의 역사를 화석을 통해 추정한다. 사람의 먼 조상은 4백만년 전에 나타났고 이집트에서는 5천년 전 뇌수술을 한 흔적이 당시의 두개골에 나타나 있으며 남아메리카 원주민들도 흑요석 칼로 뇌수술했다.

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Provenance Estimation on the Yeoncheon Samgeori Obsidian Artifacts (연천 삼거리 유적지 흑요석제 석기에 대한 산지 추정)

  • Yi, Seonbok;Jwa, Yong-Joo;Jin, Mi-Eun;Kil, Youngwoo
    • The Journal of the Petrological Society of Korea
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    • v.28 no.4
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    • pp.299-306
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    • 2019
  • We estimated the provenance of the obsidian artifacts from Samgeori site at Yeoncheon, one of the prehistoric sites in South Korea. Pyroxene microlites are of hedenbergite to augite compositions, and intergrown and/or overgrown with Fe-oxides showing poikilitic texture. Major oxides contents for the matrix of the obsidian artifacts exhibit a narrow compositional range, especially SiO2 contents being 73.0~75.5 wt.% of acidic rhyolitic composition. Also, rare earth element (REE) contents are relatively constant in the obsidian artifacts, and the chondrite-normalized REE patterns show a strong Eu negative anomaly. These mineralogical and geochemical features of the Samgeori obsidian artifacts were compared with those from both the Baekdusan obsidians and Japanese Kyushu obsidians which have been thought to be two major obsidian provenances around South Korea. It is suggested that the Samgeori obsidian artifacts were possibly originated from the Baekdusan obsidians.