Between my two excellent tours and Wikipedia I have learned a lot. For example, mate, terere, and the difference between the two.
First I should mention Guaraní (pronounced Goo-a-rah-NI), is the name of and the language of the local people and the name of the money. The language is widely used and many Guaraní words are part of the Spanish vocabulary, including mate and terere.
So mate “is prepared by steeping dried leaves of yerba mate in hot water and is served with a metal straw from a shared hollow calabash gourd.” People are drinking mate now from a metal cup with leather insulation.
And terere “is an infusion of yerba mate, similar to mate but prepared with cold water and ice rather than with hot, and in a slightly larger vessel.” I’ve been seeing everyone drink terere out of uninsulated metal cups.
You just put the chopped yerba mate leaves into the cup, pour water over, hot or cold depending, and then drink the beverage through the straw. You can see the way the leaves get filtered out through the straw in the lower left.
Also notice the thermoses, large and small, found in every car and beside every person who is just sitting around. One drinks mate only in the early morning and terere all day long.