More than 3,000 miles away, among the craggy slopes linking Marrakech with the coastal port of Essaouira, is the epicenter of the decade’s defining beauty ingredient. It’s here, under the scorching Moroccan sun, that cooperatives of Berber women harvest the gnarled nuts of the argan tree, grinding them into a thick brown paste between two slabs of rock before the oil is extracted by hand and transformed into the final product: bottles of glossy argan oil destined for the hair and skin of consumers around the world.

“It really has become one of the biggest buzzwords in beauty,” says Courtney Denelle, store manager of the Aveda Experience Center in Back Bay. “Although many people think of the oil as a hair smoother, for us it’s always been about skincare—which is why it’s the backbone of our Green Science line of creams and serums.”

With a list of benefits that reads like a who’s who of antiaging (think vitamin E, beta-carotene, squalene, and ferulic acid, an antioxidant that has increased potency under UV rays) as well as a reputation for being a fix-all for everything from acne and psoriasis to eczema and wrinkles, it’s little surprise that the number of oil adopters grows by the day.

Of course, it’s Moroccanoil that can be credited with kick-starting the trend stateside in 2006, with the launch of Moroccanoil Treatment—an instantaneous argan-rich hair smoother that now sells in more than 30 countries worldwide. “It’s hands down the best product for treating unruly hair,” says Alex Safar, the co-owner of Salon Àcôté. “My staff even use it in the winter to alleviate dry skin on their hands. It’s such an incredible product.” But hair was just the start. Now Moroccanoil’s cofounder, Carmen Tal, is segueing the über-ingredient into a luxe body care range (12 products will launch this summer alone). For Tal integrating the oil into our beauty routines was a no-brainer. She had discovered its benefits after the oil restored her color-damaged hair to silky perfection, but it’s skincare benefits were clear from the moment she visited the Berber women who coordinate the harvests. “You have women of 70 cracking the argan nuts,” says Tal, “but their hands look like those of 20-year-olds.”

And now word is spreading: It’s the lynchpin ingredient of Kiehl’s Superbly Restorative Argan range (customers at the brand’s Newbury street store love the multitasking Dry Oil); Bumble and Bumble’s big launch of the summer, Hairdresser’s Invisible Oil, contains argan oil; and both Gwyneth Paltrow and Rachel Weisz are devotees of Ila-Spa, a botanic-rich range that uses the oil in many of its formulas. Even L’Oréal will succumb this July with the introduction of EverSleek Precious Oil Treatment, designed to smooth troublesome hair for 48 hours.

“It’s been a runaway success,” BlueMercury cofounder Marla Malcolm Beck says of the public’s growing fixation with the Moroccan import. “I started using it on my kids’ and my own hair one holiday many years ago, and I was converted. Now I use it post-shower and post-beach all throughout the summer on our long hair.” Beck has cherry-picked Moroccanoil’s new body cream and scrub for her Hingham store.

Over at the 11-room Exhale Mind Body Spa in Battery Warf, which opened just 14 months ago, mind body spa director Kim Vaughn sees their range of argan products, Kahina Giving Beauty, literally fly off the shelves. “We are constantly selling out of the eye cream,” she moans, saying of the entire range, “Our guests just want to bathe in it!” Continuing the Moroccan theme, the spa has a hammam where visitors can indulge in a traditional brisk exfoliation before or after a facial or massage.

Denelle views argan as part of Aveda’s increasing focus on botanicals. “When you’re smoothing your hair or skin with synthetics, it’s just like sticking a band-aid over the problem,” she says. “You’re improving the appearance but not actually fixing anything long-term. These oils like argan, jojoba, sunflower, and meadowfoam seed penetrate to the subcutaneous layers, so they are about more than just instant gratification.”

The sheer demand for the oil has been a boon for the female-run groups who produce it (still using the same centuries-old techniques, which take several days to produce just one single liter of liquid). And now that their 10,000-square-mile argan-growing region has been deemed a biosphere reserve by Unesco, their future has been assured. Whether they can keep pace with the world’s rampant demand for the product is another question. Perhaps one day Bostonians will be getting their argan fix from the sunny slopes of California.