Secret of Cerulean Sand

is a Japanese anime television series by Telecom Animation Film and TMS Entertainment. It aired in WOWWOW from 5 January to June 2002. The series is loosely based on the novels by Jules Verne; "The Barsac Mission" (L’Étonnante Aventure de la mission Barsac) from 1919 and "Facing the Flag" (Face au drapeau) from 1896.

Plot
Jane Buxton is a 15-year-old English girl who dreams of building a flying machine with her older brother, George. But then George and their stepbrother, William mysteriously disappears after leaving on an eastern expedition to discover a mysterious cerulean sand which can make machines fly, but reported to be executed for treason. Jane still believes her brother is alive and is determined to prove his innocence.

After receiving an unsigned letter holding a handful of pale-blue sand which floats in the air, Jane sets off to the East to find his whereabouts while unraveling many mysteries in store for her and her new friends. But perhaps a mystery should forever remain a mystery...

Official
TMS ENTERTAINMENT

Other Sources
Myanimelist.net