Sorry, but it's not actually Austrian, but it probably is a thaler. It was struck by the Austrians for use in their Dutch territories, the "Austrian Netherlands". It's a kronenthaler, struck in Vienna (Austria). It's KM#22 in the 18th century Krause. I said "probably" because the ½ kronenthaler had an identical design. Is it dollar-sized or half-dollar sized?
That's a quite well worn example, and it may have been cleaned some time ago - not an uncommon fate for larger silver coins of this period. The silver quality is .873 or thereabouts.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis