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火山岩・深成岩の組織と、マグマの化学組成・鉱物組合せを分けて火成岩を整理します。",{"id":33,"type":34,"term":19,"definition":35,"plainExplanation":36,"keywords":37},"definition","DefinitionBlock","火成岩はマグマが冷え固まった岩石で、冷え方による組織とマグマの組成によって多様になります。","地表付近で急に冷えると細かな結晶やガラスを含む火山岩、地下でゆっくり冷えると大きな結晶が組み合わさる深成岩になります。一方、明るい色か暗い色か、どの鉱物が多いかは主にマグマの化学組成と関係します。",[20,21,38,39],"組成が鉱物組合せに影響","二軸を混同しない",{"id":41,"type":42,"title":43,"points":44,"body":45},"key-point","KeyPointBlock","組織の軸と組成の軸を分ける",[20,21,38,39],"標本問題では、先に結晶の大きさがそろうかを見て冷却環境を判断し、次に色や鉱物から組成傾向を読みます。火山岩だから必ず暗色、深成岩だから必ず明色ではありません。 資料では凡例・軸・観測条件を先に確認し、見えた事実とそこからの推論を別の文にして、結論の根拠がどの値や位置関係にあるかを示します。",{"id":47,"type":48,"src":49,"alt":50,"caption":51},"diagram","DiagramBlock","\u002Fassets\u002Fhigh-school\u002Fbasic-earth-science\u002Factive-earth\u002Figneous-rock-diversity\u002Figneous-rock-diversity.svg","火成岩を冷却場所と組織、マグマ組成と鉱物組合せの二軸で比較する図","上段で地表付近の急冷と地下の徐冷から結晶組織を判断し、下段でマグマ組成から明色・暗色鉱物の割合を読む二つの軸を分けます。",{"id":53,"type":54,"steps":55,"title":60},"steps","StepBlock",[56,57,58,59],"標本の結晶粒の大きさとそろい方を見る","急冷又は徐冷の環境を推定する","色と代表鉱物を観察する","組織と組成の二軸から岩石の特徴を説明する","資料を判断する手順",{"id":62,"type":63,"columns":64,"rows":68,"summary":81},"compare","CompareBlock",[65,66,67],"対象","特徴・条件","判断の意味",[69,73,77],[70,71,72],"火山岩","地表付近で急冷","細かな石基など",[74,75,76],"深成岩","地下で徐冷","大きな結晶",[78,79,80],"組成差","マグマの化学組成","鉱物・色の傾向","冷却速度は主に組織、マグマ組成は主に鉱物組合せへ表れるため、同じ一軸に並べません。",{"id":83,"type":84,"scenario":85,"explanation":86,"result":87},"example","ExampleBlock","標本Aは大きな結晶が互いに組み合い、標本Bは細かな部分の中に大きな結晶が点在していた。","Aは全体がゆっくり冷えた深成岩の組織と考えられます。Bは地下で一部の結晶が育った後、地表付近で残りが急冷した斑状組織と読めます。ただし色の違いを判断するには、別に鉱物組合せも観察する必要があります。","Aは徐冷、Bは二段階の冷却という組織の証拠を読み、組成判断とは分けられます。",{"id":89,"type":90,"warningTitle":91,"message":92,"severity":93,"action":94},"warning","WarningBlock","色だけで火山岩と深成岩を決めない","火山岩・深成岩の区別は主に冷却場所と組織です。明るい・暗いという色はマグマ組成の手掛かりで、冷却場所の分類とは別の軸です。","info","結晶組織を先、色と鉱物を後に観察しましょう。",{"id":96,"type":97,"title":98,"questions":99},"quiz","QuizBlock","確認テスト",[100],{"question":101,"choices":102,"answerIndex":106,"choiceExplanations":107},"大きな結晶が全体に組み合わさる組織から推定しやすい冷却環境はどれですか。",[103,104,105],"地下でゆっくり冷えた","地表で瞬時に全て気体になった","水に溶けたまま固まらなかった",0,[108,109,110],"正解です。結晶が成長する時間が長い徐冷を示します。","火成岩はマグマが冷え固まった岩石で、気体だけにはなりません。","結晶をもつ固体岩石なので、溶液のままではありません。",{"id":112,"type":113,"title":114,"points":115},"summary","SummaryBlock","まとめ",[116,117,118,119],"火成岩はマグマが冷え固まってできる","冷却速度が組織へ表れる","組成が鉱物組合せと色へ表れる","組織と組成を二軸で判断する",{"id":121,"type":122,"title":123,"nextTopics":124,"relatedKeywords":126},"next-action","NextActionBlock","次は「プレート境界とプレート内の地震」へ",[125],"high-school-basic-earth-science-active-earth-earthquakes-at-boundaries-and-within-plates",[127,128,129],"境界の固着と急なずれ","内陸活断層でも発生","沈み込む板内でも発生",{"path":10,"title":18,"description":131,"parentPath":132,"accentToken":133},"プレート運動、大地形と地質構造、火山活動、火成岩、変成岩、地震を関連付けるカテゴリです。","\u002Fhigh-school\u002Fbasic-earth-science","signal-orange",{"title":135,"description":136,"canonicalUrl":137,"ogImage":138},"火成岩の多様性とマグマ 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