<P> The abundance of elements in Earth's crust is shown in tabulated form with the estimated crustal abundance for each chemical element shown as either percentage or parts per million (ppm) by mass (10,000 ppm = 1%). </P> <Table> Abundance of chemical elements in Earth's crust, from various sources <Tr> <Th> Rank </Th> <Th_colspan="3"> Z, element & symbol </Th> <Th_colspan="5"> Abundance in crust (ppm) by source </Th> <Th> Annual production </Th> </Tr> <Tr> <Th> </Th> <Th> </Th> <Th> </Th> <Th> </Th> <Th> Darling </Th> <Th> Barbalace </Th> <Th> WebElements </Th> <Th> Israel Science and Technology </Th> <Th> Jefferson Lab </Th> <Th> (2016, tonnes) </Th> </Tr> <Tr> <Td> </Td> <Td> 8 </Td> <Td> oxygen </Td> <Td> </Td> <Td> 466,000 </Td> <Td> 474,000 </Td> <Td> 460,000 </Td> <Td> 467,100 </Td> <Td> 461,000 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> 14 </Td> <Td> silicon </Td> <Td> Si </Td> <Td> 277,200 </Td> <Td> 277,100 </Td> <Td> 270,000 </Td> <Td> 276,900 </Td> <Td> 282,000 </Td> <Td> 7,200,000 </Td> </Tr> <Tr> <Td> </Td> <Td> 13 </Td> <Td> aluminium </Td> <Td> Al </Td> <Td> 81,300 </Td> <Td> 82,000 </Td> <Td> 82,000 </Td> <Td> 80,700 </Td> <Td> 82,300 </Td> <Td> 57,600,000 </Td> </Tr> <Tr> <Td> </Td> <Td> 26 </Td> <Td> iron </Td> <Td> Fe </Td> <Td> 50,000 </Td> <Td> 41,000 </Td> <Td> 63,000 </Td> <Td> 50,500 </Td> <Td> 56,300 </Td> <Td> 1,150,000,000 </Td> </Tr> <Tr> <Td> 5 </Td> <Td> 20 </Td> <Td> calcium </Td> <Td> Ca </Td> <Td> 36,300 </Td> <Td> 41,000 </Td> <Td> 50,000 </Td> <Td> 36,500 </Td> <Td> 41,500 </Td> <Td> </Td> </Tr> <Tr> <Td> 6 </Td> <Td> 11 </Td> <Td> sodium </Td> <Td> Na </Td> <Td> 28,300 </Td> <Td> 23,000 </Td> <Td> 23,000 </Td> <Td> 27,500 </Td> <Td> 23,600 </Td> <Td> 255,000,000 </Td> </Tr> <Tr> <Td> 7 </Td> <Td> 12 </Td> <Td> magnesium </Td> <Td> Mg </Td> <Td> 20,900 </Td> <Td> 23,000 </Td> <Td> 29,000 </Td> <Td> 20,800 </Td> <Td> 23,300 </Td> <Td> 1,010,000 </Td> </Tr> <Tr> <Td> 8 </Td> <Td> 19 </Td> <Td> potassium </Td> <Td> </Td> <Td> 25,900 </Td> <Td> 21,000 </Td> <Td> 15,000 </Td> <Td> 25,800 </Td> <Td> 20,900 </Td> <Td> </Td> </Tr> <Tr> <Td> 9 </Td> <Td> 22 </Td> <Td> titanium </Td> <Td> Ti </Td> <Td> 4,400 </Td> <Td> 5,600 </Td> <Td> 6,600 </Td> <Td> 6,200 </Td> <Td> 5,600 </Td> <Td> 6,600,000 </Td> </Tr> <Tr> <Td> 10 </Td> <Td> </Td> <Td> hydrogen </Td> <Td> </Td> <Td> 1,400 </Td> <Td> </Td> <Td> 1,500 </Td> <Td> 1,400 </Td> <Td> 1,400 </Td> <Td> </Td> </Tr> <Tr> <Td> 11 </Td> <Td> 15 </Td> <Td> phosphorus </Td> <Td> </Td> <Td> 1,200 </Td> <Td> 1,000 </Td> <Td> 1,000 </Td> <Td> 1,300 </Td> <Td> 1,050 </Td> <Td> </Td> </Tr> <Tr> <Td> 12 </Td> <Td> 25 </Td> <Td> manganese </Td> <Td> Mn </Td> <Td> 1,000 </Td> <Td> 950 </Td> <Td> 1,100 </Td> <Td> 900 </Td> <Td> 950 </Td> <Td> 16,000,000 </Td> </Tr> <Tr> <Td> 13 </Td> <Td> 9 </Td> <Td> fluorine </Td> <Td> </Td> <Td> 800 </Td> <Td> 950 </Td> <Td> 540 </Td> <Td> 290 </Td> <Td> 585 </Td> <Td> </Td> </Tr> <Tr> <Td> 14 </Td> <Td> 56 </Td> <Td> barium </Td> <Td> Ba </Td> <Td> 500 </Td> <Td> 340 </Td> <Td> 340 </Td> <Td> 500 </Td> <Td> 425 </Td> <Td> </Td> </Tr> <Tr> <Td> 15 </Td> <Td> 6 </Td> <Td> carbon </Td> <Td> </Td> <Td> 300 </Td> <Td> 480 </Td> <Td> 1,800 </Td> <Td> 940 </Td> <Td> 200 </Td> <Td> </Td> </Tr> <Tr> <Td> 16 </Td> <Td> 38 </Td> <Td> strontium </Td> <Td> Sr </Td> <Td> </Td> <Td> 370 </Td> <Td> 360 </Td> <Td> </Td> <Td> 370 </Td> <Td> 350,000 </Td> </Tr> <Tr> <Td> 17 </Td> <Td> 16 </Td> <Td> sulfur </Td> <Td> </Td> <Td> 500 </Td> <Td> 260 </Td> <Td> 420 </Td> <Td> 520 </Td> <Td> 350 </Td> <Td> 69,300,000 </Td> </Tr> <Tr> <Td> 18 </Td> <Td> 40 </Td> <Td> zirconium </Td> <Td> Zr </Td> <Td> </Td> <Td> 190 </Td> <Td> 130 </Td> <Td> 250 </Td> <Td> 165 </Td> <Td> 1,460,000 </Td> </Tr> <Tr> <Td> 19 </Td> <Td> 74 </Td> <Td> tungsten </Td> <Td> </Td> <Td> </Td> <Td> 160.6 </Td> <Td> 1.1 </Td> <Td> </Td> <Td> 1.25 </Td> <Td> 86,400 </Td> </Tr> <Tr> <Td> 20 </Td> <Td> 23 </Td> <Td> vanadium </Td> <Td> V </Td> <Td> 100 </Td> <Td> 160 </Td> <Td> 190 </Td> <Td> </Td> <Td> 120 </Td> <Td> 76,000 </Td> </Tr> <Tr> <Td> 21 </Td> <Td> 17 </Td> <Td> chlorine </Td> <Td> Cl </Td> <Td> 500 </Td> <Td> 130 </Td> <Td> 170 </Td> <Td> 450 </Td> <Td> 145 </Td> <Td> </Td> </Tr> <Tr> <Td> 22 </Td> <Td> 24 </Td> <Td> chromium </Td> <Td> Cr </Td> <Td> 100 </Td> <Td> 100 </Td> <Td> 140 </Td> <Td> 350 </Td> <Td> 102 </Td> <Td> 26,000,000 </Td> </Tr> <Tr> <Td> 23 </Td> <Td> 37 </Td> <Td> rubidium </Td> <Td> Rb </Td> <Td> 300 </Td> <Td> 90 </Td> <Td> 60 </Td> <Td> </Td> <Td> 90 </Td> <Td> </Td> </Tr> <Tr> <Td> 24 </Td> <Td> 28 </Td> <Td> nickel </Td> <Td> Ni </Td> <Td> </Td> <Td> 80 </Td> <Td> 90 </Td> <Td> 190 </Td> <Td> 84 </Td> <Td> 2,250,000 </Td> </Tr> <Tr> <Td> 25 </Td> <Td> 30 </Td> <Td> zinc </Td> <Td> Zn </Td> <Td> </Td> <Td> 75 </Td> <Td> 79 </Td> <Td> </Td> <Td> 70 </Td> <Td> 11,900,000 </Td> </Tr> <Tr> <Td> 26 </Td> <Td> 29 </Td> <Td> copper </Td> <Td> Cu </Td> <Td> 100 </Td> <Td> 50 </Td> <Td> 68 </Td> <Td> </Td> <Td> 60 </Td> <Td> 19,400,000 </Td> </Tr> <Tr> <Td> 27 </Td> <Td> 58 </Td> <Td> cerium </Td> <Td> Ce </Td> <Td> </Td> <Td> 68 </Td> <Td> 60 </Td> <Td> </Td> <Td> 66.5 </Td> <Td> </Td> </Tr> <Tr> <Td> 28 </Td> <Td> 60 </Td> <Td> neodymium </Td> <Td> Nd </Td> <Td> </Td> <Td> 38 </Td> <Td> 33 </Td> <Td> </Td> <Td> 41.5 </Td> <Td> </Td> </Tr> <Tr> <Td> 29 </Td> <Td> 57 </Td> <Td> lanthanum </Td> <Td> La </Td> <Td> </Td> <Td> 32 </Td> <Td> 34 </Td> <Td> </Td> <Td> 39 </Td> <Td> </Td> </Tr> <Tr> <Td> 30 </Td> <Td> 39 </Td> <Td> yttrium </Td> <Td> Y </Td> <Td> </Td> <Td> 30 </Td> <Td> 29 </Td> <Td> </Td> <Td> 33 </Td> <Td> 6,000 </Td> </Tr> <Tr> <Td> 31 </Td> <Td> 7 </Td> <Td> nitrogen </Td> <Td> </Td> <Td> 50 </Td> <Td> 25 </Td> <Td> 20 </Td> <Td> </Td> <Td> 19 </Td> <Td> 140,000,000 </Td> </Tr> <Tr> <Td> 32 </Td> <Td> 27 </Td> <Td> cobalt </Td> <Td> Co </Td> <Td> </Td> <Td> 20 </Td> <Td> 30 </Td> <Td> </Td> <Td> 25 </Td> <Td> 123,000 </Td> </Tr> <Tr> <Td> 33 </Td> <Td> </Td> <Td> lithium </Td> <Td> Li </Td> <Td> </Td> <Td> 20 </Td> <Td> 17 </Td> <Td> </Td> <Td> 20 </Td> <Td> 35,000 </Td> </Tr> <Tr> <Td> 34 </Td> <Td> 41 </Td> <Td> niobium </Td> <Td> Nb </Td> <Td> </Td> <Td> 20 </Td> <Td> 17 </Td> <Td> </Td> <Td> 20 </Td> <Td> 64,000 </Td> </Tr> <Tr> <Td> 35 </Td> <Td> 31 </Td> <Td> gallium </Td> <Td> Ga </Td> <Td> </Td> <Td> 18 </Td> <Td> 19 </Td> <Td> </Td> <Td> 19 </Td> <Td> </Td> </Tr> <Tr> <Td> 36 </Td> <Td> 21 </Td> <Td> scandium </Td> <Td> Sc </Td> <Td> </Td> <Td> 16 </Td> <Td> 26 </Td> <Td> </Td> <Td> 22 </Td> <Td> </Td> </Tr> <Tr> <Td> 37 </Td> <Td> 82 </Td> <Td> lead </Td> <Td> Pb </Td> <Td> </Td> <Td> 14 </Td> <Td> 10 </Td> <Td> </Td> <Td> 14 </Td> <Td> 4,820,000 </Td> </Tr> <Tr> <Td> 38 </Td> <Td> 62 </Td> <Td> samarium </Td> <Td> Sm </Td> <Td> </Td> <Td> 7.9 </Td> <Td> 6 </Td> <Td> </Td> <Td> 7.05 </Td> <Td> </Td> </Tr> <Tr> <Td> 39 </Td> <Td> 90 </Td> <Td> thorium </Td> <Td> Th </Td> <Td> </Td> <Td> 12 </Td> <Td> 6 </Td> <Td> </Td> <Td> 9.6 </Td> <Td> </Td> </Tr> <Tr> <Td> 40 </Td> <Td> 59 </Td> <Td> praseodymium </Td> <Td> Pr </Td> <Td> </Td> <Td> 9.5 </Td> <Td> 8.7 </Td> <Td> </Td> <Td> 9.2 </Td> <Td> </Td> </Tr> <Tr> <Td> 41 </Td> <Td> 5 </Td> <Td> boron </Td> <Td> </Td> <Td> </Td> <Td> 950 </Td> <Td> 8.7 </Td> <Td> </Td> <Td> 10 </Td> <Td> 9,400,000 </Td> </Tr> <Tr> <Td> 42 </Td> <Td> 64 </Td> <Td> gadolinium </Td> <Td> Gd </Td> <Td> </Td> <Td> 7.7 </Td> <Td> 5.2 </Td> <Td> </Td> <Td> 6.2 </Td> <Td> </Td> </Tr> <Tr> <Td> 43 </Td> <Td> 66 </Td> <Td> dysprosium </Td> <Td> Dy </Td> <Td> </Td> <Td> 6 </Td> <Td> 6.2 </Td> <Td> </Td> <Td> 5.2 </Td> <Td> </Td> </Tr> <Tr> <Td> 44 </Td> <Td> 72 </Td> <Td> hafnium </Td> <Td> Hf </Td> <Td> </Td> <Td> 5.3 </Td> <Td> 3.3 </Td> <Td> </Td> <Td> 3.0 </Td> <Td> </Td> </Tr> <Tr> <Td> 45 </Td> <Td> 68 </Td> <Td> erbium </Td> <Td> Er </Td> <Td> </Td> <Td> 3.8 </Td> <Td> 3.0 </Td> <Td> </Td> <Td> 3.5 </Td> <Td> </Td> </Tr> <Tr> <Td> 46 </Td> <Td> 70 </Td> <Td> ytterbium </Td> <Td> Yb </Td> <Td> </Td> <Td> 3.3 </Td> <Td> 2.8 </Td> <Td> </Td> <Td> 3.2 </Td> <Td> </Td> </Tr> <Tr> <Td> 47 </Td> <Td> 55 </Td> <Td> caesium </Td> <Td> Cs </Td> <Td> </Td> <Td> </Td> <Td> 1.9 </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> 48 </Td> <Td> </Td> <Td> beryllium </Td> <Td> Be </Td> <Td> </Td> <Td> 2.6 </Td> <Td> 1.9 </Td> <Td> </Td> <Td> 2.8 </Td> <Td> 220 </Td> </Tr> <Tr> <Td> 49 </Td> <Td> 50 </Td> <Td> tin </Td> <Td> Sn </Td> <Td> 0 </Td> <Td> 2.2 </Td> <Td> 2.2 </Td> <Td> </Td> <Td> 2.3 </Td> <Td> 280,000 </Td> </Tr> <Tr> <Td> 50 </Td> <Td> 63 </Td> <Td> europium </Td> <Td> Eu </Td> <Td> </Td> <Td> 2.1 </Td> <Td> 1.8 </Td> <Td> </Td> <Td> 2.0 </Td> <Td> </Td> </Tr> <Tr> <Td> 51 </Td> <Td> 92 </Td> <Td> uranium </Td> <Td> U </Td> <Td> </Td> <Td> 0 </Td> <Td> 1.8 </Td> <Td> </Td> <Td> 2.7 </Td> <Td> 74,119 </Td> </Tr> <Tr> <Td> 52 </Td> <Td> 73 </Td> <Td> tantalum </Td> <Td> Ta </Td> <Td> </Td> <Td> </Td> <Td> 1.7 </Td> <Td> </Td> <Td> 2.0 </Td> <Td> 1,100 </Td> </Tr> <Tr> <Td> 53 </Td> <Td> 32 </Td> <Td> germanium </Td> <Td> Ge </Td> <Td> </Td> <Td> 1.8 </Td> <Td> 1.4 </Td> <Td> </Td> <Td> 1.5 </Td> <Td> 155 </Td> </Tr> <Tr> <Td> 54 </Td> <Td> 42 </Td> <Td> molybdenum </Td> <Td> Mo </Td> <Td> </Td> <Td> 1.5 </Td> <Td> 1.1 </Td> <Td> </Td> <Td> 1.2 </Td> <Td> 227,000 </Td> </Tr> <Tr> <Td> 55 </Td> <Td> 33 </Td> <Td> arsenic </Td> <Td> As </Td> <Td> </Td> <Td> 1.5 </Td> <Td> 2.1 </Td> <Td> </Td> <Td> 1.8 </Td> <Td> 36,500 </Td> </Tr> <Tr> <Td> 56 </Td> <Td> 67 </Td> <Td> holmium </Td> <Td> Ho </Td> <Td> </Td> <Td> 1.4 </Td> <Td> 1.2 </Td> <Td> </Td> <Td> 1.3 </Td> <Td> </Td> </Tr> <Tr> <Td> 57 </Td> <Td> 65 </Td> <Td> terbium </Td> <Td> Tb </Td> <Td> </Td> <Td> 1.1 </Td> <Td> 0.94 </Td> <Td> </Td> <Td> 1.2 </Td> <Td> </Td> </Tr> <Tr> <Td> 58 </Td> <Td> 69 </Td> <Td> thulium </Td> <Td> Tm </Td> <Td> </Td> <Td> 0.48 </Td> <Td> 0.45 </Td> <Td> </Td> <Td> 0.52 </Td> <Td> </Td> </Tr> <Tr> <Td> 59 </Td> <Td> 35 </Td> <Td> bromine </Td> <Td> Br </Td> <Td> </Td> <Td> 0.37 </Td> <Td> </Td> <Td> </Td> <Td> 2.4 </Td> <Td> 391,000 </Td> </Tr> <Tr> <Td> 60 </Td> <Td> 81 </Td> <Td> thallium </Td> <Td> Tl </Td> <Td> </Td> <Td> 0.6 </Td> <Td> 0.530 </Td> <Td> </Td> <Td> 0.850 </Td> <Td> 10 </Td> </Tr> <Tr> <Td> 61 </Td> <Td> 71 </Td> <Td> lutetium </Td> <Td> Lu </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> 0.5 </Td> <Td> </Td> </Tr> <Tr> <Td> 62 </Td> <Td> 51 </Td> <Td> antimony </Td> <Td> Sb </Td> <Td> </Td> <Td> 0.2 </Td> <Td> 0.2 </Td> <Td> </Td> <Td> 0.2 </Td> <Td> 130,000 </Td> </Tr> <Tr> <Td> 63 </Td> <Td> 53 </Td> <Td> iodine </Td> <Td> </Td> <Td> </Td> <Td> 0.14 </Td> <Td> 0.490 </Td> <Td> </Td> <Td> 0.450 </Td> <Td> 31,600 </Td> </Tr> <Tr> <Td> 64 </Td> <Td> 48 </Td> <Td> cadmium </Td> <Td> Cd </Td> <Td> </Td> <Td> 0.11 </Td> <Td> 0.15 </Td> <Td> </Td> <Td> 0.15 </Td> <Td> 23,000 </Td> </Tr> <Tr> <Td> 65 </Td> <Td> 47 </Td> <Td> silver </Td> <Td> Ag </Td> <Td> </Td> <Td> 0.070 </Td> <Td> 0.080 </Td> <Td> </Td> <Td> 0.075 </Td> <Td> 27,000 </Td> </Tr> <Tr> <Td> 66 </Td> <Td> 80 </Td> <Td> mercury </Td> <Td> Hg </Td> <Td> </Td> <Td> 0.05 </Td> <Td> 0.067 </Td> <Td> </Td> <Td> 0.085 </Td> <Td> 4,500 </Td> </Tr> <Tr> <Td> 67 </Td> <Td> 34 </Td> <Td> selenium </Td> <Td> Se </Td> <Td> </Td> <Td> 0.05 </Td> <Td> 0.05 </Td> <Td> </Td> <Td> 0.05 </Td> <Td> 2,200 </Td> </Tr> <Tr> <Td> 68 </Td> <Td> 49 </Td> <Td> indium </Td> <Td> In </Td> <Td> </Td> <Td> 0.049 </Td> <Td> 0.160 </Td> <Td> </Td> <Td> 0.250 </Td> <Td> 655 </Td> </Tr> <Tr> <Td> 69 </Td> <Td> 83 </Td> <Td> bismuth </Td> <Td> Bi </Td> <Td> </Td> <Td> 0.048 </Td> <Td> 0.025 </Td> <Td> </Td> <Td> 0.0085 </Td> <Td> 10,200 </Td> </Tr> <Tr> <Td> 70 </Td> <Td> 52 </Td> <Td> tellurium </Td> <Td> Te </Td> <Td> </Td> <Td> 0.005 </Td> <Td> 0.001 </Td> <Td> </Td> <Td> 0.001 </Td> <Td> 2,200 </Td> </Tr> <Tr> <Td> 71 </Td> <Td> 78 </Td> <Td> platinum </Td> <Td> Pt </Td> <Td> </Td> <Td> 0.003 </Td> <Td> 0.0037 </Td> <Td> </Td> <Td> 0.005 </Td> <Td> 172 </Td> </Tr> <Tr> <Td> 72 </Td> <Td> 79 </Td> <Td> gold </Td> <Td> Au </Td> <Td> </Td> <Td> 0.0011 </Td> <Td> 0.0031 </Td> <Td> </Td> <Td> 0.004 </Td> <Td> 3,100 </Td> </Tr> <Tr> <Td> 73 </Td> <Td> 44 </Td> <Td> ruthenium </Td> <Td> Ru </Td> <Td> </Td> <Td> 0.001 </Td> <Td> 0.001 </Td> <Td> </Td> <Td> 0.001 </Td> <Td> </Td> </Tr> <Tr> <Td> 74 </Td> <Td> 46 </Td> <Td> palladium </Td> <Td> Pd </Td> <Td> </Td> <Td> 0.0006 </Td> <Td> 0.0063 </Td> <Td> </Td> <Td> 0.015 </Td> <Td> 208 </Td> </Tr> <Tr> <Td> 75 </Td> <Td> 75 </Td> <Td> rhenium </Td> <Td> Re </Td> <Td> </Td> <Td> 0.0004 </Td> <Td> 0.0026 </Td> <Td> </Td> <Td> 0.0007 </Td> <Td> 47.2 </Td> </Tr> <Tr> <Td> 76 </Td> <Td> 77 </Td> <Td> iridium </Td> <Td> Ir </Td> <Td> </Td> <Td> 0.0003 </Td> <Td> 0.0004 </Td> <Td> </Td> <Td> 0.001 </Td> <Td> </Td> </Tr> <Tr> <Td> 77 </Td> <Td> 45 </Td> <Td> rhodium </Td> <Td> Rh </Td> <Td> </Td> <Td> 0.0002 </Td> <Td> 0.0007 </Td> <Td> </Td> <Td> 0.001 </Td> <Td> </Td> </Tr> <Tr> <Td> 78 </Td> <Td> 76 </Td> <Td> osmium </Td> <Td> Os </Td> <Td> </Td> <Td> 0.0001 </Td> <Td> 0.0018 </Td> <Td> </Td> <Td> 0.0015 </Td> <Td> </Td> </Tr> </Table> <Tr> <Th> Rank </Th> <Th_colspan="3"> Z, element & symbol </Th> <Th_colspan="5"> Abundance in crust (ppm) by source </Th> <Th> Annual production </Th> </Tr>

What are the two most abundant elements in earth's crust