Answer:
The material is silica quartz.
Explanation:
Given that,
Speed of light in material 
Speed of light in vacuum
We need to calculate the refractive index
Using formula of refractive index

Where, c = Speed of light in vacuum
v=Speed of light in material
Put the value into the formula


We know that,
Refractive index of silica quartz is between 1.40 to 1.55
So, This is the refractive index of silica quartz.
Hence, The material is silica quartz.