In this post I’ll show you how to enable a new file type in SharePoint
Open the folder C:Program FilesCommon Filesmicrosoft sharedWeb Server Extensions15TEMPLATEIMAGES on your SharePoint server.
Now add your custom icon image file to the IMAGES folder
Stop your IIS by IISRESET Stop
And then associate the icon image the file extension we need to add an entry to the DOCICON file.
Edit the file C:Program FilesCommon Filesmicrosoft sharedWeb Server Extensions15TEMPLATEXMLDOCICON.XML
Finally check on your SharePoint Search if this kind of files has been added to be crawled.
Hope it helps!