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.
The file system might not be in the beginning of the raw partition image.
First you need to convert the image from sparse to raw, using either simg2img or sparse_img_to_ext4.py.
Then, you need to find the beginning of the actual partition, binwalk is my favorite tool for that:
$ binwalk super.raw.img

DECIMAL       HEXADECIMAL     DESCRIPTION
--------------------------------------------------------------------------------
1048576       0x100000        Linux EXT filesystem, rev 3.0, ext2 filesystem data, UUID=8f83745e-c212-5aab-a776-4aeed9fad9fa, volume name &quot;/&quot;
[...many many irrlevant hits...]

Now you can mount the file system using the first offset from the binwalk output:
sudo mount super.raw.img -t ext4 -o ro,loop,offset=0x100000 /media/super/