I just came across this forum looking for updated articles on Loki Patera. I wanted to add a little bit of what I believe from a volcanologists standpoint of what we've observed at Loki Patera. I have been working on Loki Patera for almost 3 years as my Master's thesis research. What I've come to understand is that Loki Patera is a silicate volcano based on the NIMS and PPR data as well as modeled brightness temperatures in excess of 1000 K (Davies, GRL, 2003). Sulfur boils at temperatures around 400 K and the temperatures we've measured are way too high for a sulfur lava lake. <br />Also, the "raft" or "island" I don't think is a raft. Comparing the images that Voyager and Galileo took of Loki Patera, the "island" does not change shape, location or size in the roughly 20 years between missions and since we do have ground-based observations that show that Loki Patera has been active in between those missions, if the "island" were a raft we should see some change in at the very least location based on the convecting lava lake theory. Also, the PPR data and NIMS data should show warmer surface temperatures than they do for the "island" instead the "island" has the same surface temperature as the surrounding plains. Also, the cracks across the "island" make this a unique feature on Io (this is not seen anywhere else on Io). These cracks are shown to have a warm component to them based on the NIMS data. On Earth, this may indicate a resurgent dome. I think this is a theory that should be looked into further for Loki Patera.