<Tr> <Th> Optical properties </Th> <Td> Biaxial (+) </Td> </Tr> <Tr> <Th> Refractive index </Th> <Td> n = 1.606--1.629 n = 1.609--1.631 n = 1.616--1.638 </Td> </Tr> <Tr> <Th> Birefringence </Th> <Td> δ = 0.010 </Td> </Tr> <Tr> <Th> Pleochroism </Th> <Td> Weak in thick sections X = yellow; Y = yellow, violet, reddish; Z = violet, bluish, yellow, pink </Td> </Tr>

What is the name of the yellow stone