Interplanetary dust particles (IDPs), collected in the Earth's stratosphere, have been a subject of intense laboratory studies for the last ten years. A significant proportion of collected IDPs has a composition close to the solar (or chondritic) elemental abundance. This paper reviews results of mineralogical, petrological and chemical studies of the chondritic IDPs. Experimental studies on mineralogy, infrared absorption spectra, and isotopic properties of the chondritic IDPs have suggested that they are primitive and may contain records of the early solar system and possibly of events that predate it. Specific mineralogical and chemical features provide indications of processes including direct condensation from the solar nebula, hydrocarbon formation in the nebula, and aqueous alteration in water-rich parent bodies. Of particular interest are the mineralogical and chemical relationships between IDPs and carbonaceous chondrites. Data of both IDPs and carbonaceous chondrites have accumulated, and it is now possible to compare the mineralogies of the IDPs and the meteorites in considerable detail. Important points of information and their implications for the origin of IDPs are discussed. The current knowledge of mineralogy and chemistry of IDPs suggests that most hydrated IDPs were derived from asteroids and most anhydrous IDPs were derived from comets.

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宇宙空間には, 一立方センチ当り10^-13個程度の固体微粒子(星間塵)がある. その存在に関する示唆は, すでに18世紀に暗黒星雲の実視観測からハーシェルによってなされていた. 光学観測が中心であった今世紀半ばまでの天文学においては, 星や散光星雲の光を背景にしてのみ星間塵の観測がなされていた. しかし, 近年の赤外線, 紫外線, 電波の観測により, 星間塵自身の諸性質およびそれを取り巻く環境がより細かく観測されるようになり, 星や太陽系の誕生等の問題に星間塵が重要な役割をはたしていることが判ってきた. ここでは, 星間塵に関する観測結果を列挙し, その組成の解明がどのように進んできたかを書いてみる.

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