is a very common carbonate about the hardness of a fingernail 3 really obvious cleavage planes that form little parallelograms

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1 Nn-silicates /10/2013 1:37:00 PM Carbnates based n carbnate in CO 3 2- Distinctin between a rck and mineral is that rck type cnveys texture, rigin, cntext, etc. and mineral classificatin is based mre n chemical prperties Calcite, r CaCO 3 is a very cmmn carbnate abut the hardness f a fingernail 3 really bvius cleavage planes that frm little parallelgrams ne f the tw minerals that shell-frming rganisms tend t frm their shells ut f rcks smetimes frm frm calcite, either with entire shells r with itty bitty pieces f calcite that were disslved and recrystallized frm shells (calcareus ze) shells are cryptcrystalline, and thus d nt make pretty rhmbi when shattered naturally clear but cntaminatin can easily change the clr bubbles when reacting with HCl because carbnates all react w/ acids t frm carbn dixide gas CaCO 3 + 2H + Ca 2+ + H 2 O + CO 2 is what s happening when bubbles happen Will fluresce under a black light Has very weird ptical prperties Birefringence light plarized ne way ges in and cmes ut a different manner than light plarized a different way Light ges in and splits int tw beams that travel at different speeds, thus bending differently and cming ut f the rck as tw separate beams f light

2 Many different rcks with calcite Marble is als smetimes 100% calcite Limestne is als calcite, is the catch-all term fr a sedimentary rck that is all limestne Whitebard chalk used t be 100% calcite, but is nw prbably calcium sulfite Als travertine bathrm rck, is banded limestne that frms almst cmpletely frm chemical precipitatin and has bands because f chemical changes in the water. Fund as and in caves

3 (stalagmites & stalactites), ht springs (large temperature changes disslve and precipitate calcite) Very pretty under plarized light Tums [nt a rck??] is als chalk, but yummy, neutralizes HCl in yur stmach and helps with heartburn Usually fund in places near seashells, s typically sedimentary rcks r metamrphic rcks with a sedimentary rigin. Generally a bilgical thing, s nt usually fund in igneus rcks Very pssibly the reasn why Earth isn t Venus Venus Venus is the sister planet f Earth, and has almst the same size and mass, which means they shuld be cmpsed f mainly the same materials Venus has an atmsphere almst 100% denser than Earth s cmpsed mainly f CO 2, with perpetual cluds Surface temperature f abut 400 degrees Mst f the carbn in Earth is tied up in carbnate rcks, while mst f the carbn in Venus is in the atmsphere, causing an extreme versin f the greenhuse effect because f the thick atmsphere, making Venus very ht and windy Mars is n the ppsite end f the spectrum, with practically n Calcite is Very Imprtant atmsphere r greenhuse effect t speak f

4 Oxides /10/2013 1:37:00 PM Irn By mass, there is mre irn than anything else in the Earth mstly because f the cre. Irn xides- quite a few but there are tw that are really imprtant; Hematite and Magnetite Cmmercially very imprtant because mst f the irn peple use is smelted frm hematite and magnetite frm banded irn frmatins (alternating bands f hematite and magnetite) Banded irn is all really ld, and is a sign f the evlutin f phtsynthesis xygen cmes frm plants; may reflect the first widespread glbal pllutin prblem (xygen is really reactive and wuld be very txic t mst early life frms) [red is hematite, black is magnetite] //tangent// insects rely n diffusin t get xygen int their bdy, and there isn t enugh xygen in the air right nw t supprt the giant bugs that nce were // Pure irn is usually nt fund n the Earth because it will rust ver time, unless it is a fairly recently fallen meterite Pure irn is nt usually used fr anything because it has a lt f pretty useless weak prducts Irn + chrmium = n rust Irn + vanadium = really hard Ldestne naturally ccurring magnetic rck Hematite: Fe 2 O 3

5 Can be turned int a magnet but des nt hld magnetism very well and fades with time Pure hematite is black Is the highest xidized state f irn, is what mst irn will eventually turn int Is very dense Streaks red Magnetite: Fe3O4 If magnetized, will stay magnetized pretty much frever Every crystal f magnetite has a magnetic field like a bar magnet, that is lcked at birth Peple can use this t tell when the Earth s magnetic ples have switched, by lking at distinctive bars in the Earth. There were really useful in prviding evidence fr sea-flr spreading; as new crust was frmed arund a rift, it wuld magnetize accrding t the plarity f the Earth at the time, and then get pushed away by newer crust, making bands n the cean flr. cl Streaks black Can be a bimineral Sme animals migrate lng distances and can navigate using magnetic fields t sme extent (birds, bees, etc) Mst rganisms that navigate magnetically have specialized cells that synthesize magnetite crystals Sme bacteria als d this t distinguish which way is up r dwn. These rganisms dn t have a clear shared ancestr, and is very likely a case f cnvergent evlutin

6 Hwever, all these rganisms make crystals abut the same size, same shape, and line them up in the same way because it s the best way t make the strngest magnet with the least mass f irn pssible Inrganic magnetite, n the ther hand, has a huge diversity f sizes and shapes. This is weird because there has been magnetite in a Martian meterite that lks very much like rganic magnetite. Peple can tell Martian rcks are frm Mars with a variety f ways. The few rcks classified as Martian release gas that was a perfect match fr Martian atmsphere when cked in a micrwave. The suspicius rck frm Mars had distinctive gechemical markers that matched with the ther Martian rcks

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