Contents of a static library

On gcc, use ar -t.

-t option of the gnu archiver (ar) writes a table of contents of archive to the standard output. Only the files specified by the file operands shall be included in the written list. If no file operands are specified, all files in archive shall be included in the order of the archive.

More info here.

You can see the contents (the .o files that went into it) and the defined symbols by using nm. If this contains C++ code you should use the -C option to demangle the symbol names:

nm -C libschnoeck.a | less