{"id":5147,"date":"2026-09-20T03:13:53","date_gmt":"2026-09-20T03:13:53","guid":{"rendered":"https:\/\/crystals.rocks\/"},"modified":"2026-09-20T05:52:48","modified_gmt":"2026-09-20T05:52:48","slug":"krotite","status":"publish","type":"post","link":"https:\/\/crystals.rocks\/sk\/article\/krotite\/","title":{"rendered":"Krotite"},"content":{"rendered":"<p>Krotit je prirodneho v\u00fdskytu oxid kalcia\u2013hlin\u00edka s ide\u00e1lnym chemick\u00fdm vzorcom <strong>CaAl\u2082O\u2084<\/strong>. Je klasifikovan\u00fd ako oxidov\u00e9 miner\u00e1l a je najm\u00e4 zn\u00e1my z vlo\u017eiek bohat\u00fdch na v\u00e1penat\u00e9 a hlin\u00edkov\u00e9 zl\u00fa\u010deniny v primit\u00edvnych uhl\u00edkov\u00fdch chondritoch. Na rozdiel od v\u00e4\u010d\u0161iny be\u017en\u00fdch terestrick\u00fdch min\u00e9r, Krotit sa zvy\u010dajne vyskytuje ako mikroskopick\u00e9 zrnie\u010dka zapusten\u00e9 v meteoritoch namiesto ve\u013ek\u00fdch, izolovan\u00fdch kry\u0161t\u00e1lov.<\/p>\n<p>Ide\u00e1lny vzorec obsahuje jeden at\u00f3m v\u00e1pnika, dva at\u00f3my hlin\u00edka a \u0161tyri at\u00f3my kysl\u00edka. Jeho teoretick\u00e9 zlo\u017eenie je pribli\u017ene 25,4 hmot. % v\u00e1pnika, 34,1 hmot. % hlin\u00edka a 40,5 hmot. % kysl\u00edka. Vyjadren\u00e9 ako oxidy zodpoved\u00e1 zlo\u017eeniu pribli\u017ene 35,5 hmot. % CaO a 64,5 hmot. % Al\u2082O\u2083. Prirodzen\u00e9 zrnie\u010dka m\u00f4\u017eu obsahova\u0165 men\u0161ie chemick\u00e9 odch\u00fdlky, ale miner\u00e1l je ur\u010den\u00fd svoj\u00edm zlo\u017een\u00edm CaAl\u2082O\u2084 a jeho charakteristickou kry\u0161t\u00e1lovou \u0161trukt\u00farou.<\/p>\n<figure id=\"attachment_5085\" aria-describedby=\"caption-attachment-5085\" style=\"width: 300px\" class=\"wp-caption alignleft\"><img fetchpriority=\"high\" decoding=\"async\" class=\"size-medium wp-image-5085\" src=\"https:\/\/crystals.rocks\/wp-content\/uploads\/2026\/09\/krotite-300x215.png\" alt=\"krotite\" width=\"300\" height=\"215\" srcset=\"\" sizes=\"(max-width: 300px) 100vw, 300px\" data-srcset=\"\" \/><figcaption id=\"caption-attachment-5085\" class=\"wp-caption-text\">krotite<\/figcaption><\/figure>\n<p>Krotit je n\u00edzko tlakov\u00fd dimorf CaAl\u2082O\u2084. Vysokotlak\u00fd dimorf sa naz\u00fdva dmitryivanovit. Tieto dva miner\u00e1ly maj\u00fa rovnak\u00fd ide\u00e1lny chemick\u00fd vzorec, ale in\u00e9 at\u00f3mov\u00e9 usporiadanie, tak\u017ee ich je potrebn\u00e9 rozli\u0161ova\u0165 kry\u0161talografick\u00fdmi met\u00f3dami namiesto len chemick\u00e9ho zlo\u017eenia. Krotit je tie\u017e \u0161truktur\u00e1lne spojen\u00fd so syntetick\u00fdmi v\u00e1penat\u00fdmi alumin\u00e1tmi pou\u017e\u00edvan\u00fdmi v odoln\u00fdch keramik\u00e1ch a v\u00e1penat\u00fdch alumin\u00e1tov\u00fdch cementoch, hoci priemyseln\u00e9 v\u00e1penat\u00e9 alum\u00ednaty nie s\u00fa automaticky trieden\u00e9 ako miner\u00e1l Krotit.<\/p>\n<h2>Historia a objavovanie krotitu<\/h2>\n<p>Krotit bol form\u00e1lne op\u00edsan\u00fd ako nov\u00e1 min\u00e9ralogia v roku 2011. Typov\u00fd materi\u00e1l poch\u00e1dza z meteoritu NWA 1934, CV3 uhl\u00edkov\u00fd chondrit z juhoz\u00e1padnej Afriky. Miner\u00e1l sa vyskytuje v inkl\u00fazii bohatom na v\u00e1pnik a hlin\u00edk, ktor\u00e1 sa be\u017ene skr\u00e1ti ako CAI. Tieto inkluzie s\u00fa medzi najodolnej\u0161\u00edmi komponentami zachovan\u00fdmi v primit\u00edvnych chondritick\u00fdch meteoritoch.<\/p>\n<p>Miner\u00e1l bol pomenovan\u00fd pod\u013ea Alexandra N. Krot, kozmoch\u00e9ma, ktor\u00e9ho v\u00fdskum sa zameriaval na chondritick\u00e9 meteority, refrakt\u00e1rne zlo\u017eky, kondenz\u00e1ciu procesy a ran\u00fa chemick\u00fa evol\u00faciu Slne\u010dnej s\u00fastavy. Miner\u00e1l bol schv\u00e1len\u00fd Medzin\u00e1rodnou mineralogickou asoci\u00e1ciou pod ozna\u010den\u00edm IMA 2010-038.<\/p>\n<p>P\u00f4vodn\u00e9 opis vyu\u017e\u00edval chemick\u00fa anal\u00fdzu, elektr\u00f3nov\u00fa mikrosk\u00f3piu, krystalografiu a petrografick\u00e9 pozorovania. T\u00e1to kombin\u00e1cia bola potrebn\u00e1, preto\u017ee zrny Krotitu s\u00fa mal\u00e9 a vyskytuj\u00fa sa v komplexnej zmesi oxidov v\u00e1pnika\u2013hlin\u00edka, silik\u00e1tov a in\u00fdch odoln\u00fdch f\u00e1z. Chemick\u00e1 anal\u00fdza bl\u00edzka CaAl\u2082O\u2084 by sama o sebe nebola dostato\u010dn\u00e1, preto\u017ee niektor\u00e9 pr\u00edbuzn\u00e9 miner\u00e1ly maj\u00fa podobn\u00e9 element\u00e1rne pomery alebo sa m\u00f4\u017eu vyskytn\u00fa\u0165 v tej istej meteoritovej inkl\u00fazii.<\/p>\n<h2>Vznik a geologick\u00e9 v\u00fdskyt krotitu<\/h2>\n<p>Krotity vznikaj\u00fa pri vysok\u00fdch teplot\u00e1ch a n\u00edzkom tlaku v silne odolnom chemickom prostred\u00ed. Zahrnutie Krotitu v NWA 1934 sa interpretuje ako produkt kondenz\u00e1cie alebo krystaliz\u00e1cie z hor\u00faceho plynu v ranom slne\u010dnom mlhovine. Rozvaha o f\u00e1zovom rovnov\u00e1he ukazuje na vznik pri teplot\u00e1ch pribli\u017ene 1500 \u00b0C alebo vy\u0161\u0161\u00edch pri n\u00edzkom tlaku. Tieto podmienky s\u00fa v s\u00falade so vznikom odoln\u00fdch pevn\u00fdch l\u00e1tok pred kondenz\u00e1ciou mnoh\u00fdch viac volatiln\u00fdch prvkov a miner\u00e1lov.<\/p>\n<p>Kalcium a hlin\u00edk s\u00fa medzi najmenej volatiln\u00fdmi hlavn\u00fdmi prvkami v slne\u010dnom mlhovine. Ke\u010f sa hor\u00faca nebularn\u00e1 plyn ochladil, tieto prvky mohli reagova\u0165 s kysl\u00edkom za vzniku odoln\u00fdch oxidov a kalcium-hlin\u00edkov\u00fdch silik\u00e1tov. Krotit teda zaznamen\u00e1vaj\u00fa vysokoteplotn\u00fd stupe\u0148 tvorby miner\u00e1lov, ktor\u00fd prebehol pred zlo\u017een\u00edm materskej asteroidu meteoritu. Jeho vznik by nemal by\u0165 zamie\u0148an\u00fd s be\u017en\u00fdmi terestrick\u00fdmi magmatick\u00fdmi, hydroterm\u00e1lnymi alebo metamorfn\u00fdmi procesmi.<\/p>\n<p>V NWA 1934 je krotit zameran\u00fd v strednej a mantelovej \u010dasti neobvykle bohat\u00e9ho na v\u00e1pnik\u2013hlin\u00edk zahrnutia. Vyskytuje sa spolu s perovskitom, gehlenitom, hercynitom, mayenitom, grossitom, hibonitom, spinelom a diopsidom. Boli tie\u017e spr\u00e1vane stopov\u00e9 hexamolybdenum. Minera\u013en\u00e1 asociovanos\u0165 ukazuje, \u017ee zahrnutie pre\u0161lo nieko\u013ek\u00fdmi f\u00e1zami kondenz\u00e1cie, krystaliz\u00e1cie, reakcie a pravdepodobne \u010diasto\u010dn\u00e9ho tavenia namiesto vzniku jednou jednoduchou reakciou.<\/p>\n<p>Extern\u00e1 \u010das\u0165 zahrnutia bola op\u00edsan\u00e1 ako maj\u00faca vzh\u013ead pretrhanej \u0161krupiny alebo \u201epretrhnut\u00e9ho vajca\u201c. Niektor\u00e9 trhliny s\u00fa vyplnen\u00e9 oxidmi \u017eeleza a hlin\u00edka. Tieto hydratovan\u00e9 miner\u00e1ly sa interpretuj\u00fa ako produkty terestrick\u00e9ho po\u010dasia, ktor\u00e9 nastalo po tom, \u010do meteorit dosiahol Zem. Nemaj\u00fa by\u0165 pova\u017eovan\u00e9 za prim\u00e1rne produkty prostredia slne\u010dnej s\u00fastavy. T\u00e1to rozdielna je d\u00f4le\u017eit\u00e1, preto\u017ee po\u010dasie m\u00f4\u017ee meni\u0165 hranice a povrchy p\u00f4vodn\u00fdch zrn Krotitu.<\/p>\n<h2>Kristalick\u00e1 \u0161trukt\u00fara krotitu<\/h2>\n<p>Krotit kry\u0161talizuje sa v monoklinickom kry\u0161t\u00e1lovom syst\u00e9me. Jeho spr\u00e1van\u00fd priestorov\u00fd skupina je <strong>P2\u2081\/n<\/strong>, skupina priestoru 14. Parametre jednotkovej buny ur\u010den\u00e9 pre typov\u00fd materi\u00e1l s\u00fa pribli\u017ene <strong>a = 8,6996(3) \u00c5<\/strong>, <strong>b = 8,0994 (3) \u00c5<\/strong>, <strong>c = 15,217(1) \u00c5<\/strong>, a <strong>\u03b2 = 90,188(6)\u00b0<\/strong>. Jednotkov\u00e1 bunka obsahuje dvan\u00e1s\u0165 vzorcov\u00fdch jednotiek, vyjadren\u00e9 ako <strong>Z = 12<\/strong>a m\u00e1 vypo\u010d\u00edtan\u00fd objem pribli\u017ene 1 071 \u00c5\u00b3.<\/p>\n<p>\u0160trukt\u00fara sa d\u00e1 op\u00edsa\u0165 v\u0161eobecne ako r\u00e1mec dominovan\u00fd hlin\u00edk-oxidov\u00fdmi polyhedrami, najm\u00e4 AlO\u2084 tetrahedrami, pri\u010dom v\u00e1pnik zauj\u00edma v\u00e4\u010d\u0161ie \u0161truktur\u00e1lne miesta vo vn\u00fatri r\u00e1mu. Usporiadanie nie je ekvivalentn\u00e9 \u0161trukt\u00fare spinelu, aj ke\u010f chemick\u00fd vzorec m\u00e1 v\u0161eobecn\u00fa stochiometrick\u00fa vz\u0165ah jedn\u00e9ho dvojhodnotn\u00e9ho kat\u00f3du s dvoma trojhodnotn\u00fdmi kat\u00f3dami a \u0161tyrmi at\u00f3mami kysl\u00edka.<\/p>\n<p>Rozdiel medzi krotitom a dmitryivanovitom je \u0161truktur\u00e1lny, nie kompozi\u010dn\u00fd. Obe f\u00e1zy maj\u00fa vzorec CaAl\u2082O\u2084, ale s\u00fa stabiln\u00e9 pri r\u00f4znych tlakoch a maj\u00fa in\u00e9 usporiadanie at\u00f3mov. Krotit predstavuje formu pri ni\u017e\u0161om tlaku, zatia\u013e \u010do dmitryivanovit je spojen\u00fd s vy\u0161\u0161\u00edmi tlakmi.<\/p>\n<p>Preto\u017ee prirodzene Krotit sa vyskytuje ako mal\u00e9 zrnie\u010dka uzatvoren\u00e9 in\u00fdmi miner\u00e1lmi, dobre vyvinut\u00e9 vonkaj\u0161ie krystalick\u00e9 plochy s\u00fa nebe\u017en\u00e9. \u0160truktur\u00e1lna inform\u00e1cia sa teda zvy\u010dajne z\u00edska pomocou r\u00f6ntgenovej difrakcie, elektr\u00f3novej difrakcie alebo elektr\u00f3novej difrakcie odrazu. Tieto met\u00f3dy s\u00fa obzvl\u00e1\u0161\u0165 u\u017eito\u010dn\u00e9, ke\u010f s\u00fa zrnie\u010dka pr\u00edli\u0161 mal\u00e9 na konven\u010dn\u00fd anal\u00fdzu jednoduch\u00e9ho kry\u0161t\u00e1lu.<\/p>\n<h2>Fyzik\u00e1lne a chemick\u00e9 vlastnosti krotitu<\/h2>\n<p>Krotit sa zvy\u010dajne pozoruje ako mikroskopick\u00e9 zrny v polirovan\u00fdch rezoch alebo tenk\u00fdch rezoch. Opisy jeho farby a lesku s\u00fa menej diagnostick\u00e9 ako jeho chemick\u00e9 zlo\u017eenie a kry\u0161talick\u00e1 \u0161trukt\u00fara, preto\u017ee vonkaj\u0161\u00ed vzh\u013ead z\u00e1vis\u00ed od hr\u00fabky zrn, orient\u00e1cie, okolit\u00fdch min\u00e9r\u00e1l a alter\u00e1cie. Prirodzen\u00fd materi\u00e1l m\u00f4\u017ee pod svetlom prech\u00e1dzaj\u00facim alebo odrazn\u00fdm vyzera\u0165 bezfarebn\u00fd a\u017e po svetlohned\u00fd, pri\u010dom hranice jednotliv\u00fdch zrn m\u00f4\u017eu by\u0165 v komplexn\u00fdch inkl\u00fazi\u00e1ch \u0165a\u017eko rozoznate\u013en\u00e9.<\/p>\n<p>Zaznamenana tvrdos\u0165 pod\u013ea Mohsa je pribli\u017ene 6,5 a vypo\u010d\u00edtan\u00e1 hustota je pribli\u017ene 2,94 g\/cm\u00b3. Priama meranie hustoty je n\u00e1ro\u010dn\u00e9, preto\u017ee zrny s\u00fa ve\u013emi mal\u00e9 a \u010dasto s\u00fa medzi sebou prepojen\u00e9 s in\u00fdmi f\u00e1zami. V\u00fdrazovanie a lom s\u00fa tie\u017e \u0165a\u017ek\u00e9 na spo\u013eahliv\u00e9 vyhodnotenie na jednotliv\u00fdch zrn\u00e1ch z toho ist\u00e9ho d\u00f4vodu.<\/p>\n<p>Ide\u00e1lna chemick\u00e1 zlo\u017eenie je CaAl\u2082O\u2084. Elektr\u00f3novo-mikroprieskumov\u00e9 anal\u00fdzy by mali obvykle ukazova\u0165 pomer v\u00e1pnika k hlin\u00edku bl\u00edzky 1:2, po zoh\u013eadnen\u00ed kysl\u00edka a analytick\u00e9ho neistoty. Men\u0161ie mno\u017estv\u00e1 hor\u010d\u00edka, krem\u00edka, titanu, \u017eeleza, sod\u00edka alebo in\u00fdch prvkov m\u00f4\u017eu by\u0165 v stopov\u00fdch mno\u017estv\u00e1ch alebo m\u00f4\u017eu by\u0165 sp\u00f4soben\u00e9 kontamin\u00e1ciou susedn\u00fdmi miner\u00e1lmi. Tieto men\u0161ie komponenty neautomaticky definuj\u00fa samostatn\u00fa variantu Krotitu.<\/p>\n<p>Krotit je stabiln\u00fd iba v ur\u010ditom poli tlaku-teploty-kompoz\u00edcie. Pri vy\u0161\u0161\u00edch tlakoch m\u00f4\u017ee CaAl\u2082O\u2084 nadobudn\u00fa\u0165 \u0161trukt\u00faru dmitryivanovitu. V r\u00f4znych chemick\u00fdch podmienkach sa v\u00e1penat\u00e9 a hlin\u00edkov\u00e9 m\u00f4\u017eu namiesto toho forma\u0165 grossit, hibonit, gehlenit, mayenit, perovskit alebo in\u00e9 v\u00e1penato-hlin\u00edkov\u00e9 oxidy a silik\u00e1ty.<\/p>\n<h2>Typy a druhy Krotite<\/h2>\n<p>Krotit nem\u00e1 form\u00e1lne uzn\u00e1van\u00e9 druhov\u00e9 kame\u0148ov\u00e9 alebo komer\u010dn\u00e9 farby. Nasleduj\u00face kateg\u00f3rie s\u00fa opisn\u00e9, nie ofici\u00e1lne mineralogick\u00e9 podrobnosti:<\/p>\n<ul>\n<li><strong>Meteoritick\u00fd krotit:<\/strong> Prirodzene krotity vyskytuj\u00face sa v hlin\u00edkov\u00fdch zlo\u017een\u00fdch inkl\u00fazi\u00e1ch uhl\u00edkovo bohat\u00fdch chondritov, vr\u00e1tane typov\u00e9ho materi\u00e1lu z NWA 1934.<\/li>\n<li><strong>N\u00edzkonap\u00e4\u0165ov\u00fd CaAl\u2082O\u2084:<\/strong> Krotit je n\u00edzko tlakom \u0161truktur\u00e1lne forma CaAl\u2082O\u2084.<\/li>\n<li><strong>Vysokotlak\u00e9 CaAl\u2082O\u2084:<\/strong> Dmitryivanovite je vysokotlakov\u00fd dimorf CaAl\u2082O\u2084. Je to samostatn\u00e1 miner\u00e1lna \u0161pecie, nie varieta Krotitu.<\/li>\n<li><strong>Syntetick\u00fd v\u00e1penat\u00fd oxid alumin\u00e1t:<\/strong> Laborat\u00f3rne vyr\u00e1ban\u00fd CaAl\u2082O\u2084 m\u00f4\u017ee by\u0165 chemicky alebo \u0161truktur\u00e1lne podobn\u00fd Krotitu, ale ide o umel\u00fd materi\u00e1l namiesto prirodzen\u00e9ho miner\u00e1lov\u00e9ho v\u00fdskytu.<\/li>\n<\/ul>\n<p>Rozdiely v ve\u013ekosti zrn, obsahu stopov\u00fdch prvkov, alter\u00e1cii a sprev\u00e1dzaj\u00facich min\u00e9rach m\u00f4\u017eu vyvola\u0165 r\u00f4zne vzh\u013eady v jednotliv\u00fdch vzork\u00e1ch meteoritov. Tieto rozdiely opisuj\u00fa geologick\u00fd dejepis z\u0155n a nevyjadruj\u00fa ofici\u00e1lne pomenovan\u00e9 odrody.<\/p>\n<h2>Kde sa Krotite nach\u00e1dza?<\/h2>\n<p>Najlep\u0161ie dokumentovan\u00e9 pr\u00edrodn\u00e9 v\u00fdskyt Krotitu je kalciov\u00e9\u2013hlin\u00edkov\u00e9 zahrnutie v meteorite NWA 1934 CV3 uhl\u00edkatom chondrite. Meteorit bol z\u00edskan\u00fd v severoz\u00e1padnej Afrike, ale samotn\u00e9 Krotit sa vytvorilo ove\u013ea sk\u00f4r v Slnocnej s\u00fastave, pravdepodobne v oblasti vysok\u00fdch tepl\u00f4t slne\u010dnej mlhoviny.<\/p>\n<p>V meteorite Krotit sa vyskytuje hlavne v strednej a mantlovej \u010dasti refrakt\u00e1rneho zahrnutia. Spolu s miner\u00e1lmi ako perovskit, gehlenit, hercynit, mayenit, grossit, hibonit, spinel a diopsid. Tieto miner\u00e1ly spolo\u010dne poskytuj\u00fa d\u00f4kazy o vysokoteplotnej kondenz\u00e1cii a krystaliz\u00e1cii procesoch zapojen\u00fdch do v\u00e1pnika, hlin\u00edka, titanu, hor\u010d\u00edka, krem\u00edka a kysl\u00edka.<\/p>\n<p>Krotit by sa nemal zamie\u0148a\u0165 s terestri\u00e1lnym miner\u00e1lom, ktor\u00fd vznikol na mieste, kde bol meteorit z\u00edskan\u00fd. Terestri\u00e1lny pohyb meteoritu ovplyvnil vonkaj\u0161ie \u010dasti zahrnutia hydrat\u00e1ciou a oxid\u00e1ciou, ale prim\u00e1rne zrn\u00e1 Krotitu vznikli predt\u00fdm, ne\u017e existovala matersk\u00e1 teleso meteoritu. Nie je zn\u00e1ma \u017eiadna \u0161iroko uzn\u00e1van\u00e1 terestri\u00e1lna geologick\u00e1 lokalita spojen\u00e1 s Krotitom.<\/p>\n<h2>Ako identifikova\u0165 Krotite<\/h2>\n<p>Krotit sa norm\u00e1lne ned\u00e1 identifikova\u0165 nepriamym vizu\u00e1lnym sk\u00faman\u00edm. Zrnek\u00e1 s\u00fa mal\u00e9, \u010dasto s\u00fa zrejme prepojen\u00e9 s in\u00fdmi odoln\u00fdmi f\u00e1zami a m\u00f4\u017eu pripom\u00edna\u0165 niektor\u00e9 oxidy a silik\u00e1ty v\u00e1pnika a hlin\u00edka. Preto sa pou\u017e\u00edva petrografick\u00e9 sk\u00famanie ako prv\u00fd krok, za n\u00edm chemick\u00e9 a krystalografick\u00e9 anal\u00fdzy.<\/p>\n<p>Mikroskopia tenk\u00e9ho alebo polrovan\u00e9ho rezu m\u00f4\u017ee odhali\u0165 tvar zrn, kontakty, z\u00f3novanie, ne\u010distoty a vz\u0165ahy s okolit\u00fdmi miner\u00e1lmi. Obr\u00e1zovanie sp\u00e4tn\u00e9ho elektr\u00f3nu v skenuj\u00facom elektr\u00f3novom mikroskope je u\u017eito\u010dn\u00e9, preto\u017ee f\u00e1zy s r\u00f4znymi priemern\u00fdmi at\u00f3mov\u00fdmi \u010d\u00edslami vytv\u00e1raj\u00fa r\u00f4zne \u00farovne kontrastu obrazu. To umo\u017e\u0148uje n\u00e1js\u0165 oblasti bohat\u00e9 na krotit pred kvantitat\u00edvnym anal\u00fdzou.<\/p>\n<p>Elektr\u00f3nov\u00e1 mikroprobn\u00e1 anal\u00fdza sa norm\u00e1lne pou\u017e\u00edva na ur\u010denie koncentr\u00e1ci\u00ed v\u00e1pnika, hlin\u00edka, kysl\u00edka pomocou \u0161t\u00f6chiometrick\u00e9ho v\u00fdpo\u010dtu a ak\u00fdchko\u013evek pr\u00edslu\u0161n\u00fdch prvkov. Anal\u00fdzy by mali by\u0165 vykon\u00e1van\u00e9 vzdialene od zrnit\u00fdch hran\u00edc, preto\u017ee kontamin\u00e1cia z gehlenitu, hibonitu, grossitu, mayenitu alebo in\u00fdch susedn\u00fdch miner\u00e1lov m\u00f4\u017ee vies\u0165 k nespr\u00e1vnej kompoz\u00edcii.<\/p>\n<p>Kry\u0161talografick\u00e9 potvrdenie je po\u017eadovan\u00e9, ke\u010f rozdiel medzi s\u00favisl\u00fdmi f\u00e1zami je d\u00f4le\u017eit\u00fd. R\u00f6ntgenov\u00e1 difrakcia, elektr\u00f3nov\u00e1 difrakcia a elektr\u00f3nov\u00e1 difrakcia zozadu m\u00f4\u017eu by\u0165 pou\u017eit\u00e9 na sk\u00fa\u0161anie monoklinickej \u0161trukt\u00fary a jej kompatibility so priestorovou skupinou P2\u2081\/n. Jednoduch\u00fd spektr\u00e1lny pr\u00edslu\u0161enstvo r\u00f6ntgenov\u00e9ho \u017eiarenia je zvy\u010dajne nedostato\u010dn\u00e9, najm\u00e4 ke\u010f je zrnko iba nieko\u013eko mikrometrov v priemere.<\/p>\n<p>D\u00f4le\u017eit\u00e9 miner\u00e1ly, ktor\u00e9 je potrebn\u00e9 rozli\u0161ova\u0165 od Krotitu, s\u00fa grossit, CaAl\u2084O\u2087; hibonit, CaAl\u2081\u2082O\u2081\u2089; a gehlenit, Ca\u2082Al\u2082SiO\u2087. Mayenit sa m\u00f4\u017ee vyskytova\u0165 aj v t\u00fdch ist\u00fdch refrakt\u00e1rnych zlo\u017ek\u00e1ch. Dmitryivanovit vy\u017eaduje \u0161peci\u00e1lnu pozornos\u0165, preto\u017ee m\u00e1 rovnak\u00fd ide\u00e1lny chemick\u00fd vzorec ako Krotit, ale in\u00fa krystalick\u00fa \u0161trukt\u00faru.<\/p>\n<h2>Aplik\u00e1cie a pou\u017eitie Krotitu<\/h2>\n<p>Prirodzene Krotit nem\u00e1 stanoven\u00e9 pou\u017eitie ako drahokam, dekorat\u00edvny materi\u00e1l, priemyseln\u00e1 surovina alebo samostatne \u0165a\u017een\u00e1 ruda. Jeho zrnek je pr\u00edli\u0161 mal\u00fdch a pr\u00edli\u0161 zriedkav\u00fdch na komer\u010dn\u00e9 v\u00fd\u0165a\u017eky. Miner\u00e1l sa norm\u00e1lne \u0161tuduje ako s\u00fa\u010das\u0165 sekci\u00ed meteoritov a vlo\u017eiek bohat\u00fdch na v\u00e1penat\u00e9 a hlin\u00edkov\u00e9 l\u00e1tky.<\/p>\n<p>Jeho hlavn\u00fd v\u00fdznam je analytick\u00fd a kosmochemick\u00fd. Vlo\u017eky obsahuj\u00face krotit poskytuj\u00fa inform\u00e1cie o vysokoteplotnej kondenz\u00e1cii, tvorbe miner\u00e1lov kalcium\u2013aluminium, zlo\u017een\u00ed plynov\u00e9ho mlie\u010dika a podmienkach tlaku a teploty, ktor\u00e9 existovali v najskor\u0161\u00edch f\u00e1zach hist\u00f3rie Slnkovskej s\u00fastavy. Poskytuje tie\u017e prirodzen\u00fd referen\u010dn\u00fd bod na porovnanie extraterestri\u00e1lnych miner\u00e1lnych f\u00e1z s experiment\u00e1lne syntetizovan\u00fdmi kalciov\u00fdmi alumin\u00e1tmi.<\/p>\n<p>Syntetick\u00e9 CaAl\u2082O\u2084 a pr\u00edbuzn\u00e9 v\u00e1penat\u00e9 alumin\u00e1ty sa pou\u017e\u00edvaj\u00fa v odoln\u00fdch keramik\u00e1ch, vysokoteplotn\u00fdch lepiacich l\u00e1tkach a v\u00e1penat\u00fdch alumin\u00e1tov\u00fdch cementoch. Tieto priemyseln\u00e9 aplik\u00e1cie sa t\u00fdkaj\u00fa v\u00fdrobn\u00fdch materi\u00e1lov s kontrolovan\u00fdmi zlo\u017eeniami a hist\u00f3riami spracovania. Nie s\u00fa priamymi komer\u010dn\u00fdmi aplik\u00e1ciami pr\u00edrodn\u00e9ho Krotitu.<\/p>\n<p>Krotite m\u00f4\u017eu tie\u017e pom\u00f4c\u0165 rozl\u00ed\u0161i\u0165 prim\u00e1rne nebularn\u00e9 vlastnosti od neskor\u0161\u00edch zmen\u00ed. Zrno zachovan\u00e9 vo vn\u00fatri odoln\u00e9ho zahrnutia m\u00f4\u017ee zachova\u0165 d\u00f4kazy o vysokoteplotnom vzniku, zatia\u013e \u010do jeho okraje m\u00f4\u017eu by\u0165 zmenen\u00e9 hydrot\u00e1ciou, oxid\u00e1ciou alebo terestri\u00e1lnym po\u010das\u00edm. Mineralogick\u00e1 interpret\u00e1cia mus\u00ed teda zoh\u013eadni\u0165 ako prim\u00e1rnu kry\u0161t\u00e1lov\u00fa \u0161trukt\u00faru, tak neskor\u0161\u00ed dejov\u00fd pr\u00edbeh meteoritu.<\/p>\n<h2>S\u00favisiace miner\u00e1ly a nomenklatura<\/h2>\n<p>Krotit patr\u00ed do \u0161ir\u0161ej skupiny odoln\u00fdch v\u00e1penato-almuniov\u00fdch miner\u00e1lov n\u00e1jden\u00fdch v primit\u00edvnych meteoritoch. Medzi ne patria hibonit, grossit, perovskit, spinel, gehlenit a mayenit. Rozli\u0161uj\u00fa sa chemick\u00fdmi pomermi, \u0161truktur\u00e1lnym usporiadanim, obsahom ani\u00f3nov a podmienkami stability.<\/p>\n<p>Meno Krotit sa vz\u0165ahuje v\u00fdlu\u010dne k prirodzen\u00e9mu f\u00e1ze s n\u00edzkym tlakom CaAl\u2082O\u2084 so \u0161trukt\u00farou Krotitu. Nesmie by\u0165 pou\u017eit\u00e9 ako v\u0161eobecn\u00fd term\u00edn pre ka\u017ed\u00fd v\u00e1penat\u00fd alumin\u00e1t s rovnakou nomin\u00e1lnou zlo\u017een\u00edm. Obzvl\u00e1\u0161\u0165 dmitryivanovit je pova\u017eovan\u00fd za samostatn\u00fa miner\u00e1lnu druh, preto\u017ee predstavuje in\u00fd \u0161truktur\u00e1lny tvar CaAl\u2082O\u2084.<\/p>\n<h2>Odkazy<\/h2>\n<p>Ma, C., Kampf, A. R., Connolly, H. C., et al. (2011). \u201eKrotit, CaAl\u2082O\u2084, nov\u00e1 odoln\u00e1 miner\u00e1l z meteoritu NWA 1934.\u201c <em>American Mineralogist<\/em>, 96, 709\u2013715. <a href=\"https:\/\/doi.org\/10.2138\/am.2011.3693\">https:\/\/doi.org\/10.2138\/am.2011.3693<\/a><\/p>\n<p>Mineralogick\u00e1 spolo\u010dnos\u0165 Ameriky. \u201eKrotit.\u201c <em>Pr\u00edru\u010dka pre mineral\u00f3giu<\/em>. <a href=\"https:\/\/handbookofmineralogy.org\/pdfs\/Krotite.pdf\">PDF<\/a><\/p>","protected":false},"excerpt":{"rendered":"<p>Krotite is a naturally occurring calcium\u2013aluminium oxide mineral with the ideal chemical formula CaAl\u2082O\u2084. It is classified as an oxide mineral and is primarily known from calcium\u2013aluminium-rich inclusions in primitive carbonaceous chondrites. Unlike most common terrestrial minerals, Krotite is generally present as microscopic grains embedded in meteorites rather than as large, isolated crystals. The ideal [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":5085,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_seopress_titles_title":"Krotite: Formula, Properties, Structure, and Occurrence","_seopress_titles_desc":"Krotite is a monoclinic calcium\u2013aluminium oxide mineral found in calcium\u2013aluminium-rich inclusions of carbonaceous chondrite meteorites.","_seopress_robots_index":"","_seopress_robots_follow":"","_seopress_robots_imageindex":"","_seopress_robots_snippet":"","_seopress_robots_primary_cat":"","_seopress_robots_breadcrumbs":"","_seopress_robots_freeze_modified_date":"","_seopress_robots_custom_modified_date":"","_seopress_robots_canonical":"","_seopress_social_fb_title":"","_seopress_social_fb_desc":"","_seopress_social_fb_img":"","_seopress_social_fb_img_attachment_id":0,"_seopress_social_fb_img_width":0,"_seopress_social_fb_img_height":0,"_seopress_social_twitter_title":"","_seopress_social_twitter_desc":"","_seopress_social_twitter_img":"","_seopress_social_twitter_img_attachment_id":0,"_seopress_social_twitter_img_width":0,"_seopress_social_twitter_img_height":0,"_seopress_redirections_value":"","_seopress_redirections_enabled":"","_seopress_redirections_enabled_regex":"","_seopress_redirections_logged_status":"","_seopress_redirections_param":"","_seopress_redirections_type":0,"_seopress_analysis_target_kw":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-5147","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-article"],"_links":{"self":[{"href":"https:\/\/crystals.rocks\/sk\/wp-json\/wp\/v2\/posts\/5147","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/crystals.rocks\/sk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/crystals.rocks\/sk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/crystals.rocks\/sk\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/crystals.rocks\/sk\/wp-json\/wp\/v2\/comments?post=5147"}],"version-history":[{"count":2,"href":"https:\/\/crystals.rocks\/sk\/wp-json\/wp\/v2\/posts\/5147\/revisions"}],"predecessor-version":[{"id":5149,"href":"https:\/\/crystals.rocks\/sk\/wp-json\/wp\/v2\/posts\/5147\/revisions\/5149"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/crystals.rocks\/sk\/wp-json\/wp\/v2\/media\/5085"}],"wp:attachment":[{"href":"https:\/\/crystals.rocks\/sk\/wp-json\/wp\/v2\/media?parent=5147"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/crystals.rocks\/sk\/wp-json\/wp\/v2\/categories?post=5147"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/crystals.rocks\/sk\/wp-json\/wp\/v2\/tags?post=5147"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}