Gran\u00e1t byl zn\u00e1m\u00fd a cen\u011bn\u00fd ji\u017e ve starov\u011bku \u2013 nejstar\u0161\u00ed nalezen\u00e9 gran\u00e1ty byly objeveny ve staroegyptsk\u00fdch poh\u0159ebn\u00edch \u0161perc\u00edch a v \u0159\u00edmsk\u00fdch gem\u00e1ch (ryt\u00fdch kamenech pou\u017e\u00edvan\u00fdch k vytv\u00e1\u0159en\u00ed pe\u010det\u00ed). \u0158\u00edman\u00e9 pou\u017e\u00edvali gran\u00e1ty ve sv\u00fdch pe\u010detidlech a byly tak\u00e9 obl\u00edben\u00e9 v mnoha kultur\u00e1ch jako amulety.<\/p>\n\n\n\n
N\u00e1zev gran\u00e1t poch\u00e1z\u00ed z latinsk\u00e9ho slova granatus<\/em>, co\u017e znamen\u00e1 zrno nebo zrnit\u00e9. Tento n\u00e1zev je pravd\u011bpodobn\u011b odvozen od podobnosti \u010derven\u00fdch gran\u00e1t\u016f s mal\u00fdmi sem\u00ednky gran\u00e1tov\u00e9ho jablka. <\/p>\n\n\n\n Gran\u00e1t je skupina miner\u00e1l\u016f, kter\u00e1 se skl\u00e1d\u00e1 z r\u016fzn\u00fdch chemick\u00fdch prvk\u016f, ale v\u0161echny maj\u00ed stejnou krystalickou strukturu. Gran\u00e1ty obecn\u011b krystaluj\u00ed v kubick\u00e9 (izometrick\u00e9) soustav\u011b, z \u010deho\u017e plyne, \u017ee jeho krystaly jsou \u010dasto rovnostrann\u00e9 a maj\u00ed podobu dodekaedr\u016f nebo ikositetraedr\u016f. Jeliko\u017e je gran\u00e1t skupinou miner\u00e1l\u016f s prom\u011bnliv\u00fdm chemick\u00fdm slo\u017een\u00edm, ale stejnou krystalovou strukturou (tedy nikoliv jedn\u00edm konkr\u00e9tn\u00edm koncov\u00fdm \u010dlenem), je jeho chemick\u00fd vzorec X\u2083Y\u2082(SiO\u2084)\u2083, ve kter\u00e9m X a Y zastupuj\u00ed r\u016fzn\u00e9 kationty, jako je v\u00e1pn\u00edk, \u017eelezo, ho\u0159\u010d\u00edk, mangan, hlin\u00edk nebo chrom.<\/p>\n\n\n\n Nejzn\u00e1m\u011bj\u0161\u00ed odr\u016fdy gran\u00e1tu jsou tyto:<\/p>\n\n\n\n Almandin<\/strong>, Fe2+<\/sup>3<\/sub> Al2<\/sub>(SiO4<\/sub>)3<\/sub>, je \u010derven\u00fd gran\u00e1t bohat\u00fd na \u017eelezo.<\/p>\n\n\n\n Pyrop<\/strong>, Mg3<\/sub>Al2<\/sub>(SiO4<\/sub>)3<\/sub>, je \u010derven\u00fd gran\u00e1t bohat\u00fd na ho\u0159\u010d\u00edk.<\/p>\n\n\n\n Grossul\u00e1r<\/strong>, Ca3<\/sub>Al2<\/sub>(SiO4<\/sub>)3<\/sub>, je zelen\u00fd a\u017e \u017elut\u00fd gran\u00e1t, zahrnuj\u00edc\u00ed odr\u016fdy jako tsavorit.<\/p>\n\n\n\n Spessartin<\/strong>, Mn3<\/sub>Al2<\/sub>(SiO4<\/sub>)3<\/sub>, je oran\u017eov\u00fd a\u017e \u010dervenohn\u011bd\u00fd gran\u00e1t bohat\u00fd na mangan.<\/p>\n\n\n\n Andradit<\/strong>, Ca\u2083Fe\u2082\u00b3\u207a(SiO\u2084)\u2083, v\u010detn\u011b odr\u016fdy d\u00e9mantoid, je zn\u00e1m svou zelenou barvou.<\/p>\n\n\n\n Uvarovit<\/strong>, Ca3<\/sub>Cr2<\/sub>(SiO4<\/sub>)3<\/sub>, je vz\u00e1cn\u00fd zelen\u00fd gran\u00e1t bohat\u00fd na chrom.<\/p>\n\n\n\n Miner\u00e1ly skupiny gran\u00e1tu maj\u00ed na Mohsov\u011b stupnici tvrdosti hodnotu 6,5 a\u017e 7,5, co\u017e z nich \u010din\u00ed dostate\u010dn\u011b tvrd\u00fd k\u00e1men pro v\u011bt\u0161inu klenotnick\u00fdch \u00fa\u010del\u016f, v\u010detn\u011b zasazen\u00ed do prsten\u016f, n\u00e1u\u0161nic a n\u00e1hrdeln\u00edk\u016f. Tvrdost gran\u00e1tu z\u00e1vis\u00ed na konkr\u00e9tn\u00ed odr\u016fd\u011b \u2013 nap\u0159\u00edklad almandin a pyrop jsou tvrd\u0161\u00ed ne\u017e grossul\u00e1r nebo spessartin. D\u00edky sv\u00e9 odolnosti v\u016f\u010di opot\u0159eben\u00ed je gran\u00e1t vhodn\u00fd pro ka\u017edodenn\u00ed no\u0161en\u00ed.<\/p>\n\n\n\n Gran\u00e1t je jedn\u00edm z m\u00e1la drah\u00fdch kamen\u016f, kter\u00e9 se vyskytuj\u00ed t\u00e9m\u011b\u0159 ve v\u0161ech barv\u00e1ch spektra, p\u0159i\u010dem\u017e barva gran\u00e1tu je zp\u016fsobena p\u0159\u00edm\u011bs\u00ed r\u016fzn\u00fdch kovov\u00fdch iont\u016f v jeho chemick\u00e9m slo\u017een\u00ed. Gran\u00e1t m\u00e1 relativn\u011b vysok\u00fd index lomu, kter\u00fd se pohybuje v rozmez\u00ed 1,72 a\u017e 1,94, v z\u00e1vislosti na konkr\u00e9tn\u00ed odr\u016fd\u011b. <\/p>\n\n\n\n Gran\u00e1t se tvo\u0159\u00ed v r\u016fzn\u00fdch geologick\u00fdch podm\u00ednk\u00e1ch. V\u011bt\u0161ina drahokamov\u00fdch gran\u00e1t\u016f se tvo\u0159\u00ed v metamorfovan\u00fdch hornin\u00e1ch, zejm\u00e9na v b\u0159idlic\u00edch a rul\u00e1ch, kde vznikaj\u00ed p\u0159i vysok\u00fdch tlac\u00edch a teplot\u00e1ch. Gran\u00e1t se tak\u00e9 m\u016f\u017ee nach\u00e1zet v magmatick\u00fdch hornin\u00e1ch, jako jsou pegmatity a kimberlity, kter\u00e9 jsou tak\u00e9 zdrojem diamant\u016f.<\/p>\n\n\n\n B\u011bhem procesu metamorf\u00f3zy, p\u0159i kter\u00e9m se m\u011bn\u00ed tlak a teplota, mohou gran\u00e1ty krystalizovat v hornin\u00e1ch bohat\u00fdch na hlin\u00edk a \u017eelezo. To vysv\u011btluje, pro\u010d jsou almandiny a pyropy, kter\u00e9 jsou bohat\u00e9 na tyto prvky, tak b\u011b\u017en\u00e9.<\/p>\n\n\n\n D\u00e9mantoid, jedna z nejvz\u00e1cn\u011bj\u0161\u00edch odr\u016fd gran\u00e1tu, se tvo\u0159\u00ed ve vysoce specifick\u00fdch podm\u00ednk\u00e1ch spojen\u00fdch s n\u00edzkoteplotn\u00edmi metamorfn\u00edmi horninami a serpentinity.<\/p>\n\n\n\n Gran\u00e1ty jsou \u0161iroce roz\u0161\u00ed\u0159en\u00fd miner\u00e1l a nach\u00e1z\u00ed se po cel\u00e9m sv\u011bt\u011b. N\u011bkter\u00e1 nalezi\u0161t\u011b v\u0161ak produkuj\u00ed mimo\u0159\u00e1dn\u011b kvalitn\u00ed a vz\u00e1cn\u00e9 gran\u00e1ty, kter\u00e9 jsou vysoce cen\u011bny v klenotnictv\u00ed. <\/p>\n\n\n\n Gran\u00e1ty se vyr\u00e1b\u011bj\u00ed i synteticky, ale tyto um\u011ble vyroben\u00e9 kameny neslou\u017e\u00ed k imitov\u00e1n\u00ed p\u0159\u00edrodn\u00edch gran\u00e1t\u016f.<\/p>\n","protected":false},"excerpt":{"rendered":" Historie Gran\u00e1t byl zn\u00e1m\u00fd a cen\u011bn\u00fd ji\u017e ve starov\u011bku \u2013 nejstar\u0161\u00ed nalezen\u00e9 gran\u00e1ty byly objeveny ve staroegyptsk\u00fdch poh\u0159ebn\u00edch \u0161perc\u00edch a v \u0159\u00edmsk\u00fdch gem\u00e1ch (ryt\u00fdch kamenech pou\u017e\u00edvan\u00fdch k vytv\u00e1\u0159en\u00ed pe\u010det\u00ed). \u0158\u00edman\u00e9 pou\u017e\u00edvali gran\u00e1ty ve sv\u00fdch pe\u010detidlech a byly tak\u00e9 obl\u00edben\u00e9 v mnoha kultur\u00e1ch jako amulety. N\u00e1zev gran\u00e1t poch\u00e1z\u00ed z latinsk\u00e9ho slova granatus, co\u017e znamen\u00e1 zrno nebo […]<\/p>\n","protected":false},"featured_media":7610,"template":"","meta":{"_acf_changed":false,"inline_featured_image":false},"class_list":["post-5630","kamen","type-kamen","status-publish","has-post-thumbnail","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.e-gems.cz\/en\/wp-json\/wp\/v2\/kamen\/5630","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.e-gems.cz\/en\/wp-json\/wp\/v2\/kamen"}],"about":[{"href":"https:\/\/www.e-gems.cz\/en\/wp-json\/wp\/v2\/types\/kamen"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.e-gems.cz\/en\/wp-json\/wp\/v2\/media\/7610"}],"wp:attachment":[{"href":"https:\/\/www.e-gems.cz\/en\/wp-json\/wp\/v2\/media?parent=5630"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Vlastnosti<\/h2>\n\n\n\n
Geneze<\/h2>\n\n\n\n
V\u00fdskyt<\/h2>\n\n\n\n
Syntetick\u00e1 v\u00fdroba<\/h2>\n\n\n\n