How to calculate gain of opamp with Max446 chip?
This is actually a non-inverting op-amp with a pass band filter and a DC offset cancellation.

The formula is 


  Av = 1 + R2 / R1


Where the resistor are the 100k and 10k, so you would get a gain of 11.


The first group with 1 cap and 2 1Mohm resistor are a high pass filter and decoupling.
The 100pF below the chip is a low pass filter.
The 1uF below the 10k resistor is there to remove DC offset.