[pct-l] Question about Boiling Lake

[edmond at mydogmeg.net (Edmond Meinfelder)]

When I first saw it, I wondered why Boiling Lake looked greenish. The 
question hit me again when I saw Arenal Volcano in Costa Rica 
(http://mydogmeg.net/gallery/costarica/28.html). In the volcano's crater is 
a lake much like Boiling Lake, only larger, similarly surrounded by 
fumaroles and also greenish.

Does anyone know if the greenish color is from sulphur?

(The picture of Arenal was taken with a Canon Digital Rebel using a UV 
filter in mid-day. The clarity of the photo shocked me. I was sure it would 
not come out.)

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