Myrcene
Myrcene is the most common terpene in commercial cannabis. It brings the earthy, musky, slightly fruity smell you get from a lot of classic indica-leaning strains. Strains high in myrcene are often described as relaxing and body-forward, though how any strain feels depends on the whole chemical profile, the dose and the person.
What it smells like
Earthy, musky, ripe fruit. You'll also find it in Mango, hops, lemongrass, thyme.
Boiling point
About 334°F / 168°C. If you use a temperature-controlled vaporizer, terpenes vaporize at different points, which is one reason the same flower can taste different at different settings.
A note on terpenes and effects
Terpene research in cannabis is still young. Aromas are real; claims about specific effects are generalizations. The best guide is your own experience with a strain, starting low.