<Tr> <Td> Ca </Td> <Td> 3.6 </Td> </Tr> <Tr> <Td> Na </Td> <Td> 2.8 </Td> </Tr> <Tr> <Td> </Td> <Td> 2.6 </Td> </Tr> <Tr> <Td> Mg </Td> <Td> 1.5 </Td> </Tr>

Major portion of earth crust is mainly constituted by