How to fix mount errors when trying to mount the raw image that converted from android sparse image?

I have sparse.img image with the following properties:

$ file sparse.img 
sparse.img: Android sparse image, version: 1.0, Total of 2512896 4096-byte output blocks in 60 input chunks.

I want to see its contents so - I have converted it into raw image. - Created a new directory - Trying to mount the raw image on to the directory using the following commands:

$ simg2img sparse.img sparse_raw.img
$ mkdir raw
$ sudo mount -t ext4 -o loop sparse_raw.img raw

First two commands run fine and I can see sparse_raw.img generated of size larger than sparse.img. Last command failed with an error: > wrong fs type, bad option, bad superblock on /dev/loop27, missing codepage or helper program, or other error. I think that may be the sparse_raw.img is not an ext4 image but how can I sure about it? I have tried to mount it as - ext2, ext3 or without -t - without -o loop but nothing works. Please suggest a way to fix it.