A magnetic ordering is observed for the highly doped Sr2.5Ca11.5Cu24O41, fo
r which superconductivity is expected to occur under high pressure. Cu-NMR\
NQR experiment reveals field-induced staggered hyperfine held at the chain
site, suggesting that this antiferromagnetic order of Cu spins occurs in th
e chain. (C) 2000 Elsevier Science B.V. All rights reserved.