In a cocktail shaker, combine mango juice, tequila, triple sec, and lime juice and shake until mixed.

In a small bowl, combine salt, chili powder, and lime zest and spread onto a plate. Run a lime around the rim of the glass to moisten; press rim of glass into mixture.

Drizzle about a tablespoon of chamoy into the base of the glass and swirl to coat. Fill glass with shaved or crushed ice, then pour margarita mixture over ice. Drizzle a small amount of chamoy over the drink and garnish with a lime wedge.