{"id":2737,"date":"2019-05-11T11:39:58","date_gmt":"2019-05-11T11:39:58","guid":{"rendered":"https:\/\/kamenovo.cz\/?p=2737"},"modified":"2019-05-11T12:45:43","modified_gmt":"2019-05-11T12:45:43","slug":"libyjske-sklo","status":"publish","type":"post","link":"https:\/\/kamenovo.cz\/index.php\/2019\/05\/11\/libyjske-sklo\/","title":{"rendered":"Libyjsk\u00e9 sklo"},"content":{"rendered":"

Libyjsk\u00e9 sklo<\/strong><\/a> <\/span>je zaj\u00edmav\u00e1 p\u0159\u00edrodnina pom\u011brn\u011b exotick\u00e9ho p\u016fvodu, podobn\u011b jako \u010desk\u00e9 vltav\u00edny. A stejn\u011b jako vltav\u00edny je zn\u00e1me i v podob\u011b esteticky atraktivn\u00edch uk\u00e1zek. Sv\u011btle \u017elut\u00e1 nepr\u016fhledn\u00e1 a\u017e syt\u011b \u017elutozelen\u00e1 pr\u016fsvitn\u00e1 a\u017e pr\u016fhledn\u00e1 skla velikosti od jednoho do dvaceti centimetr\u016f byla nach\u00e1zena ji\u017e v prav\u011bku a ve starov\u011bku v Libyjsk\u00e9 pou\u0161ti v oblasti tzv. Velk\u00e9ho p\u00edse\u010dn\u00e9ho mo\u0159e. Z m\u00edst v\u00fdskytu libyjsk\u00e9ho skla jsou zn\u00e1m\u00e9 drobn\u00e9 \u0161t\u00edpan\u00e9 n\u00e1stroje z tohoto materi\u00e1lu vyr\u00e1b\u011bn\u00e9 lidmi n\u011bkdy v dob\u011b p\u0159ed 30 a\u017e 18 tis\u00edci lety, tedy ve star\u0161\u00ed dob\u011b kamenn\u00e9, kdy v dan\u00e9 oblasti panovalo vl\u00eddn\u011bj\u0161\u00ed klima.<\/p>\n

<\/p>\n

Pou\u0161tn\u00ed skla byla patrn\u011b zn\u00e1ma i starov\u011bk\u00fdm Egyp\u0165an\u016fm.<\/p>\n

V roce 1922 byla v Egypt\u011b nalezena hrobka fara\u00f3na Tutanchamona \u017eij\u00edc\u00edho ve 14. stolet\u00ed p\u0159ed na\u0161\u00edm letopo\u010dtem. V jeho poh\u0159ebn\u00ed v\u00fdbav\u011b byl n\u00e1hrdeln\u00edk se \u017elut\u00fdm skarabeem, kter\u00fd je dnes ulo\u017een v Muzeu v K\u00e1hi\u0159e. Teprve a\u017e v roce 1996 bylo rozpozn\u00e1no, \u017ee skarabeus je vyroben\u00fd z libyjsk\u00e9ho pou\u0161tn\u00edho skla.<\/strong><\/span><\/a><\/p>\n

Pro v\u011bdu byla pou\u0161tn\u00ed skla objevena v roce 1932 b\u011bhem v\u00fdzkumn\u00e9 expedice veden\u00e9 P. A. Claytonem, a od t\u00e9 doby podnes se do odlehl\u00fdch m\u00edst v\u00fdskytu pou\u0161tn\u00edch skel ve v\u00fdchodn\u00ed \u010d\u00e1sti Egypta vypravily des\u00edtky dal\u0161\u00edch expedic. Jednu men\u0161\u00ed uk\u00e1zku pou\u0161tn\u00edho skla daroval ji\u017e v roce 1935 pra\u017esk\u00e9mu N\u00e1rodn\u00edmu muzeu D. H. Smith z Britsk\u00e9ho muzea v Lond\u00fdn\u011b. Darovan\u00fd vzorek nalezl v roce 1934 L. J. Spencer, kter\u00fd je spolu s v\u00fd\u0161e uveden\u00fdm P. A. Claytonem autorem v\u016fbec prvn\u00edho v\u011bdeck\u00e9ho popisu libyjsk\u00fdch skel. Spencer\u016fv vzorek je pod n\u00e1zvem lechatelierit sou\u010d\u00e1st\u00ed mineralogick\u00e9 sb\u00edrky N\u00e1rodn\u00edho muzea. Libyjsk\u00e1 skla se nach\u00e1zej\u00ed na velk\u00e9m \u00fazem\u00ed o rozloze asi
\n80 \u00d7 25 km.<\/p>\n

Le\u017e\u00ed voln\u011b na povrchu obl\u00e1zkov\u00e9 pou\u0161t\u011b zvan\u00e9 ser\u00edr<\/em> mezi vysok\u00fdmi p\u00edse\u010dn\u00fdmi dunami, kter\u00e9 po ser\u00edrov\u00e9m<\/em> podkladu pomalu putuj\u00ed. Povrch skel je obrou\u0161en p\u00edskem, un\u00e1\u0161en\u00fdm v\u011btrem, tak\u017ee skla maj\u00ed matn\u00fd, m\u011blce jamkovit\u00fd povrch. M\u00edsty jsou skla dosti hojn\u00e1 a za kr\u00e1tk\u00fd \u010das je mo\u017en\u00e9 jich nasb\u00edrat zna\u010dn\u00e9 mno\u017estv\u00ed. Nejv\u011bt\u0161\u00ed dosahuj\u00ed hmotnosti t\u0159\u00ed a\u017e \u010dty\u0159 kilogram\u016f, nalezeny byly i kusy 30 kg t\u011b\u017ek\u00e9. Takto velk\u00e9 uk\u00e1zky ov\u0161em nejsou p\u0159\u00edli\u0161 p\u011bkn\u00e9, jsou \u0161edav\u00e9 a\u017e b\u00edl\u00e9 a por\u00e9zn\u00ed. Cen\u011bn\u00e9 jsou zejm\u00e9na men\u0161\u00ed \u017elut\u00e9 pr\u016fsvitn\u00e9 a\u017e pr\u016fhledn\u00e9 vzorky, kter\u00fdch je ale jen zlomek z celkov\u00e9ho objemu. Sou\u010dasn\u00e9 expedice obvykle putuj\u00ed za pou\u0161tn\u00edmi skly do Egypta z \u00fazem\u00ed Libye. Tyto v\u00fdpravy jsou organiza\u010dn\u011b a finan\u010dn\u011b n\u00e1ro\u010dn\u00e9, oblast je dnes nav\u00edc neklidn\u00e1 a nebezpe\u010dn\u00e1.<\/p>\n

Dlouho nebylo jasn\u00e9, jak pou\u0161tn\u00ed skla vlastn\u011b vznikla a dohady o jejich p\u016fvodu trvaj\u00ed dodnes. Vysok\u00fd obsah vz\u00e1cn\u00e9ho prvku iridia<\/em> nazna\u010doval, \u017ee by mohla m\u00edt meteoritick\u00fd p\u016fvod, proto\u017ee zv\u00fd\u0161en\u00fd obsah iridia je pro meteority charakteristick\u00fd. Vnit\u0159n\u00ed struktura skel nazna\u010duje, \u017ee vznikla taven\u00edm za vysok\u00fdch teplot. Uva\u017eovalo se tedy, \u017ee vznikla p\u0159etaven\u00edm pozemsk\u00fdch p\u00eds\u010dit\u00fdch hornin p\u0159i p\u00e1du velk\u00e9ho meteoritu. Tato teorie v\u0161ak m\u011bla jednu vadu. V okol\u00ed v\u00fdskytu pou\u0161tn\u00edch skel nebyl \u017e\u00e1dn\u00fd meteoritov\u00fd kr\u00e1ter. A\u017e teprve v roce 2007 se jej p\u0159ece jenom poda\u0159ilo objevit, a to dv\u011bma v\u011bdc\u016fm z Bostonsk\u00e9 univerzity. Ti na satelitn\u00edch sn\u00edmc\u00edch Saharsk\u00e9 pou\u0161t\u011b identifikovali kruhovitou strukturu tvo\u0159enou dv\u011bma soust\u0159edn\u00fdmi prstenci mohutn\u00fdch horninov\u00fdch val\u016f. Takov\u00e1 struktura je pro meteoritov\u00e9 kr\u00e1tery typick\u00e1.<\/p>\n

Lidsk\u00e9 pozornosti unikala tato struktura zejm\u00e9na proto, \u017ee je z valn\u00e9 \u010d\u00e1sti schov\u00e1na pod mohutn\u00fdmi p\u00edse\u010dn\u00fdmi dunami Velk\u00e9ho p\u00edse\u010dn\u00e9ho mo\u0159e.<\/p>\n

\n

\"Libyjsk\u00e9Libyjsk\u00e9 pou\u0161tn\u00ed sklo, Egypt, 13x9x5 cm, sb\u00edrka N\u00e1rodn\u00edho muzea. (Foto D. Velebil)<\/p>\n<\/div>\n

Kr\u00e1ter Kebira<\/strong>, jak byl pojmenov\u00e1n, m\u00e1 pr\u016fm\u011br 31 km a le\u017e\u00ed z v\u011bt\u0161\u00ed \u010d\u00e1sti na \u00fazem\u00ed Libye, pouze jeho v\u00fdchodn\u00ed okraj zasahuje na \u00fazem\u00ed Egypta a pr\u00e1v\u011b zde jsou nach\u00e1zena pou\u0161tn\u00ed skla. Bohu\u017eel, zat\u00edm se nepoda\u0159ilo nal\u00e9zt d\u016fkazy o existenci meteoritov\u00e9ho kr\u00e1teru p\u0159\u00edmo v ter\u00e9nu. N\u011bkte\u0159\u00ed v\u011bdci proto o jeho existenci pochybuj\u00ed a vznik kruhov\u00e9 struktury p\u0159isuzuj\u00ed b\u011b\u017en\u00fdm geologick\u00fdm proces\u016fm, tj. v\u011btrn\u00e9 a vodn\u00ed erozi horizont\u00e1ln\u011b ulo\u017een\u00fdch vrstev p\u00edskovc\u016f, kter\u00e9 se uprost\u0159ed \u201ekr\u00e1teru\u201c nach\u00e1zej\u00ed a sv\u011bd\u010d\u00ed proti dopadu meteoritu v t\u011bchto m\u00edstech.<\/p>\n

Libyjsk\u00e9 pou\u0161tn\u00ed sklo<\/strong><\/span><\/a> je dnes v\u011bt\u0161inou badatel\u016f pova\u017eov\u00e1no za tzv. impaktit<\/em>.<\/p>\n

Jde o hmotu vzniklou \u0161okovou p\u0159em\u011bnou pozemsk\u00fdch hornin p\u0159i dopadu meteoritu. Impaktit\u016fm jsou bl\u00edzce p\u0159\u00edbuzn\u00e9 tektity<\/em>, tj. skla, kter\u00e1 rovn\u011b\u017e vnikla p\u0159etaven\u00edm pozemsk\u00fdch hornin v d\u016fsledku n\u00e1razu meteoritu na Zem, ov\u0161em na rozd\u00edl od impaktit\u016f prod\u011blaly tektity transport vzduchem, tak\u017ee se vyskytuj\u00ed mimo zdrojov\u00fd meteoritov\u00fd kr\u00e1ter. To je p\u0159\u00edpad i na\u0161ich vltav\u00edn\u016f<\/em>, jejich\u017e mate\u010dn\u00fdm kr\u00e1terem je Ries v Bavorsku s m\u011bstem N\u00f6rdlingen le\u017e\u00edc\u00edm uprost\u0159ed kr\u00e1teru. Existuj\u00ed i jin\u00e9 teorie vzniku libyjsk\u00fdch pou\u0161tn\u00edch skel. Uva\u017euje se nap\u0159\u00edklad, \u017ee maj\u00ed vulkanick\u00fd p\u016fvod<\/em> a \u017ee to vlastn\u011b nejsou skla, ale specifick\u00e1 forma op\u00e1lu<\/em>. Probl\u00e9m p\u016fvodu libyjsk\u00fdch pou\u0161tn\u00edch skel tedy nen\u00ed, jak se zd\u00e1, vy\u0159e\u0161en definitivn\u011b.<\/p>\n","protected":false},"excerpt":{"rendered":"

Libyjsk\u00e9 sklo je zaj\u00edmav\u00e1 p\u0159\u00edrodnina pom\u011brn\u011b exotick\u00e9ho p\u016fvodu, podobn\u011b jako \u010desk\u00e9 vltav\u00edny. A stejn\u011b jako vltav\u00edny je zn\u00e1me i v podob\u011b esteticky atraktivn\u00edch uk\u00e1zek. Sv\u011btle \u017elut\u00e1 nepr\u016fhledn\u00e1 a\u017e syt\u011b \u017elutozelen\u00e1 pr\u016fsvitn\u00e1 a\u017e pr\u016fhledn\u00e1 skla velikosti od jednoho do dvaceti centimetr\u016f byla nach\u00e1zena ji\u017e v prav\u011bku a ve starov\u011bku v Libyjsk\u00e9 pou\u0161ti v oblasti tzv. Velk\u00e9ho p\u00edse\u010dn\u00e9ho mo\u0159e. Z m\u00edst v\u00fdskytu […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0,"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"_joinchat":[],"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false},"version":2}},"categories":[18],"tags":[],"class_list":["post-2737","post","type-post","status-publish","format-standard","hentry","category-mineraly"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_likes_enabled":true,"jetpack-related-posts":[],"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p9pQSB-I9","_links":{"self":[{"href":"https:\/\/kamenovo.cz\/index.php\/wp-json\/wp\/v2\/posts\/2737","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kamenovo.cz\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kamenovo.cz\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kamenovo.cz\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kamenovo.cz\/index.php\/wp-json\/wp\/v2\/comments?post=2737"}],"version-history":[{"count":0,"href":"https:\/\/kamenovo.cz\/index.php\/wp-json\/wp\/v2\/posts\/2737\/revisions"}],"wp:attachment":[{"href":"https:\/\/kamenovo.cz\/index.php\/wp-json\/wp\/v2\/media?parent=2737"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kamenovo.cz\/index.php\/wp-json\/wp\/v2\/categories?post=2737"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kamenovo.cz\/index.php\/wp-json\/wp\/v2\/tags?post=2737"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}