Madonna Celebrates 'Humble and Kind' Daughter Mercy James on 18th Birthday: 'You Really Are a Wonder'

"I am really astounded by the woman you have become," wrote the Grammy winner

Madonna is celebrating her fourth child’s birthday with a touching tribute.

The "Vogue" singer, 65, shared a photo montage of her daughter Chifundo "Mercy" James for her 18th birthday on Monday. The sweet montage was set to background music of Mercy gracefully playing a rendition of Erik Satie’s “Gnossienne No. 1” on the piano.

“Beautiful Chifundo James! you’re 18 yrs old today!! Beautiful Mercy James. You’re already a young woman! Beautiful African Queen!! You Surprised all of us! ♥️🇲🇼♥️🇲🇼♥️🇲🇼♥️🇲🇼,” the “Material Girl” singer began her birthday message in the Instagram caption.

Madonna went on to share how Mercy has been the “quiet,” “gentle,” “shy” and “stoic” sibling and "never" wanted "to draw attention" to herself.

“Always Humble and Kind, Always the first one to say thank you. To clear the table after dinner! To Come and Hug me and say how much you appreciate something,” Madonna continued. “And Always the most Responsible.”

“I am really astounded by the woman you have become. Poised and radiant. Skilled and Soulful. A True artist,” the singer wrote.

Madonna next praised Mercy’s musical abilities. “That hand that was once frozen in your mouth as a child -now makes magic happen when you play the piano," she wrote. "Whether it's Erik Satie or Chilly Gonzales. To hear you play Chopin every night in my show with such confidence is such a thrill.”

Related: Madonna's 6 Children: Everything to Know

She then applauded Mercy’s talents behind a camera.

“Nothing gives me greater pleasure than to watch you grow. You really are A wonder,” Madonna wrote of her daughter. “Wishing You the happiest of Birthdays! The happiest of everything— because you deserve it.”

“Even though we both hate shellfish the world is your Oyster !! She is waiting for you to devour it. To eat it whole!!! To Slay it!! 🌍🌎🌏💙💙💙,” concluded the singer.

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Madonna is also mom to twins Estere and Stella, 11, David Banda, 17,  Rocco, 23, with ex-husband Guy Ritchie, and Lourdes Leon, 27, with ex Carlos Leon.

Mercy was born in Malawi on Jan. 22, 2006. After Madonna’s divorce from Ritchie was finalized in 2008, she applied to adopt Mercy as a single mother in May 2009 and was approved the next month.

Related: Madonna Joined Onstage by Five of Her Kids at the Celebration Tour Launch in London — See Photos!

In 2017, Madonna appeared on the cover of PEOPLE and opened up about her life at home with her children and her emotional adoption journey.

"Sometimes I would just close my eyes and just think, 'Why isn't my kitchen filled with dancing children?' There's so many children that need a home," she said. "I thought, 'What am I waiting for? Just do it.'"

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