Note for Mineralogy - MIN By dattatreya komakula

Topics ( 4 )

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MI NERALOGY Mi ner al :Thest udyoft hechar act er sof mi ner al s(eg:quar t z, py r oxene, amphi bol e, mi ca,chl or i t e,gar net )i s knownas Mi ner al ogy . Ami ner ali sanat ur al l yoccur r i ng homogeneous subst ance, i nor gani cal l y f or med wi t h a def i ni t e chemi cal composi t i on, wi t hacer t ai nphy si cal pr oper t i esandcr y st al l i nest r uct ur es Underf av our abl e condi t i ons,t hei nt er nalat omi cst r uct ur e ofmi ner al sr esul ti n t hedev el opmentofadef i ni t eext er nalgeomet r i cal shapei ecr y st alf or m. Thest abi l i t yof mi ner al s dependson t emper at ur e, pr essur e and chemi cal composi t i on oft heenv i r onment .Atpr esentmor et han 3000 mi ner alspeci es hav ebeen est abl i shed. Theear t h’ s cr ust i s mai nl y composed off el dspar s and quar t z and account s 55% and 10% r espect i v el y . Py r oxenes, amphi bol es, chl or i t es, mi cas, cl ay car bonat esar ewi del yspr eadt oo.Fol l owi ngaf ewr ar emi ner al sar eal socommon: Phenaci t e …Be2( Si O4) Baddel ey i t e …ZrO2 Ber t r andi t e … Be4( Si ( OH) 2O7) 4 Cor di er i t e … Hg3 S2Cl 2 Expl anat i on: Homogeneous:al lpar t soft hemi ner al sshoul dpossesst hesamephy si caland chemi calchar act er s. Cr y st al l i ne:possessat omi cst r uct ur ei nami ner al . Cr y st al :A cr y st almaybe def i ned as anat ur alsol i d bodybounded bysmoot h andpl ai nsur f aces,ar r angedgeomet r i cal l y . Cr y st al sdev el opunderf av our abl econdi t i onsdependi ngon:( 1)sl ow cool i ng( 2) sur r oundi ngs t of aci l i t at et he cr y st algr owt hi ndi f f er entdi r ect i ons.( 3)noni nt er f er encebyt headj acentgr owi ngmi ner al sdur i ngsol i di f i cat i on. Except i onsf orDef i ni t i onofMi ner al : l . Pr eci ous gemst ones l i ke di amonds,r ubi es,sapphi r es and emer al ds ar e sy nt het i cal l ypr oducedundercont r ol l edl abor at or ycondi t i ons. 2. Coal ,amber ,pet r ol eum, et c. ,ar et y pi calor gani csubst ances whi chcanbe consi der edasmi ner al s. 3.Amet hy st , smokyquar t z , ci t r i ne, cat ' sey e, av ent ur i nequar t zar esomev ar i et i esof quar t z.Col ourorappear ancepecul i ar i t yi nt hem i sbecauset heypossesssome i mpur i t i esori ncl usi onsori nhomogenei t i es. 4.Asphal t(av ar i et yofbi t umen,semi sol i di nnat ur e,bl acki ncol or ), mer cur yand nat ur algasar esemi sol i ds,l i qui dsorgases.Thought hesear ecal l edmi ner al s,t hey 1| Page

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ar enotsol i dsubst ances. 5.Agoodnumberofmi ner al sar enowf oundt obemember sofi somor phi cgr oups. I somor phi cmi ner al sdonothav eadef i ni t echemi calcomposi t i on, buthav eadef i ni t e r angeofcomposi t i on. 6.Somemi ner al sl i kef l i nt ,cher t ,j asperandagat ear ecr y pt ocr y st al l i ne,i . e. ,t heydo nothav e a wel l dev el oped cr y st alst r uct ur e.A f ew ot her sl i ke opal ,bauxi t e, Psi l omel ane,pi t chbl endeet car et y pi cal l yamor phous,i . e. ,t heydonotpossessany r egul ari nt er nalat omi cst r uct ur e. The mostwi despr eadel ement si n mi ner al s ar e:O,Si ,Al ,Fe,Ca,Na,Mg,K,Ti whi l e S,Cl ,C,Mn,H ar e moder at el yspr ead.B,Be,Pb,Sb,As,Bi ,Se,U, et c ar e ei t herr ar eear t hel ement s ornotspr eadatal l . Mi ner al sar ebr oadl ygr oupedi nt o ( a)Rockf or mi ngmi ner al s(const i t ut ear ock)and ( b)Or e–f or mi ngmi ner al s( composi t i onofanor ewhi chi seconomi cal l yi mp) . Thet er m or emi ner alembr acesmi ner al sf r om whi chv al uabl emet al l i cel ement s canbeex t r act ed.Eg;Cu,Ag, Fe,Al . Mi ner al s ar e ext r emel yi mpor t ant economi cal l y ,aest het i cal l y ,i ndust r i al l y and sci ent i f i cal l y . Economi cal l y , ut i l i zat i onof mi ner al s i s necessar yt o mai nt ai n any t hi ng f or st andar dofl i v i ng.Gol d,si l v er ,copper ,i r on,al umi num et car e economi cal l y i mpor t antmi ner al sf orhumanbei ngs. Aest het i cal l y ,mi ner al sofdi amond,r uby ,sapphi r e,emer al d shi neasgemsand enr i ch ourl i v es.Gems i nj ewel l er y , cr own j ewelcol l ect i ons at t r actt heat t ent i on ofmi l l i onsofpeopl e. Al li nal l ,appr oxi mat el y 10% ofal lmi ner alspeci es ar e used at pr esentf or i ndust r i alpur poses. Sci ent i f i cal l y , mi ner al s compr i se t he dat abankf r om whi chwecan l ear n about ourphy si calear t handi t sconst i t uentmat er i al s. Chemi st r yhasdev el oped on t hebasi soft hest udyoft hechemi calcomposi t i on andt hepr oper t i esofv ar i ousmi ner al sandor es.Mi ner al ogi calmet hodsar ewi del y usedi nPet r ol ogy ,Geochemi st r y ,soi lst udy ,Pal eont ol ogy( i nt hest udyoff ossi l s) , i nmedi ci ne, i nar cheol ogy . Al lt hemi ner al sar egr oupedi nt o8cl asses: 2| Page

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1.Nat i v eel ement s( Eg: Au, Ag, Cu, Ar seni c, Bi smut h, Pl at i num, Di amond) 2.Sul phi des (Eg: Gal ena, Py r i t e, Ci nnabar , St i bni t e, Py r r hot i t e) 3.Oxi des( Magnet i t e, Haemat i t e, Rut i l e, Br ooki t e)andhy dr oxi des( Eg: ser pent i ne; amphi bol es) 4.Hal i des( Eg: Fl uor i t e, Hal i t e) 5.Car bonat es(Eg: cal ci t e, Magnesi t e) ,ni t r at esandbor at es 6.Sul phat es(Eg: Bar y t es, Gy psum) ,chr omat es( Eg: Uv ar ov i t e) 7.Phosphat es(Eg: Apat i t e,Monazi t e) 8.Si l i cat es(eg:Quar t z ,f el dspar s,Muscov i t e,Bi ot i t e,Hor nbl ende,Tour mal i ne, Zer ol i t e, Topaz). Si nce si l i cat esar et hemost common r ockf or mi ng mi ner al s, i ti sdesi r abl et o know somer el ev antaspect saboutt hese. I nal l si l i cat e st r uct ur es,t hesi l i con at oms ar ei nf our f ol d coor di nat i onwi t h oxy gen.Thebondsbet ween si l i conandoxy gen ar esost r ong t hatt he4 oxy gen’ s ar eal way satt hecor ner sofat et r ahedr onofnear l y const antdi mensi ons. O O S O O STRUCTUREOFSI LI CATES/CLASSI FI CATI ON OFSI LI CATES Si l i cat e cl assi f i cat i onf or most si l i cat e mi ner al si s based ont het y pes of l i nkagesasf ol l ows: 1.NESOSI LI CATES 2.SOROSI LI CATES 3.I NOSI LI CATES 4.CYCLO SI LI CATES 5.PHYLLOSI LI CATES 6.TECTO SI LI CATES 3| Page

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1.NESOSI LI CATES: ( i ndependent t et r ahedr algr oups) :i nt hi s gr oup Si O4 t et r ahedr aoccurasi ndependentuni t si nmi ner alst r uct ur e. Si :O: :1: 4 Onesi l i con–oxy gent et r ahedr on Eg: Ol i v i nef ami l y ; Al umi num si l i cat ef ami l y (ky ani t e, si l l i mani t e; Andal usi t e) Gar netf ami l y . OLI VI NEFAMI LY OLI VI NES ar enesosi l i cat esi nat omi cst r uct ur ewi t ht he (Si O4) i nwhi chR=MgorFe.Ol i v i nef ami l yconsi st sof For st er i t e (Mg2Si O4) Fay al i t e (Fe2Si O4) Ol i v i ne ( MgFe) i O4 2S gener alf or mul aR2 Ol i v i nei soneoft hef i r stmi ner al st of or m al ongwi t hcal ci cpl agi ocl asef el dspar s dur i ng t hesol i di f i cat i on ofmagma.As magma cool s down,ol i v i ne r eact s wi t h si l i cacont entofpar entmagmaandchangesov ert opy r oxene. PERI DOTi sat r anspar ent , pal egr eengem v ar i et yf oundi nEgy pt ,Bur ma,Br azi l ) Al t er at i on: ol i v i nes ar e hi ghl y suscept i bl et o decomposi t i on. Hy dr ot her mal al t er at i onofol i v i nespr oducesser pent i ne. 3Mg2Si O2 +H2O +Si O2 2Mg3Si OH) 2O5( 4 For st er i t e ser pent i ne Occur r ence: Occur si n Ul t r abasi ci gneous r ocks such as Duni t e,Per i dot i t e, Pi cr i t e.Al sooccur sasaccessor ymi ner ali nBasal t s,Dol er i t es,Gabbr os. Uses:Duet oi t s hi gh mel t i ng poi nt ,ol i v i ne i s used i nt he manuf act ur eof r ef r act or ybr i cks. ALUMI NUM SI LI CATES I nnat ur e,t ot al l y ,t hr ee mi ner al s wi t h di f f er entphy si calpr oper t i es wi t h same composi t i onoccur sasAl i O5,whi char ecal l edasal umi num si l i cat es. 2S 4| Page