Formula: Ca₁₀Si₈B₂O₂₉ · 12.5H₂O

Species:

Colour: White, pale tan

Lustre: Sub-Vitreous, Silky, Dull

Hardness: 5

Specific Gravity: 2.62

Crystal System: Triclinic

Name: Named in 1984 by Isao Kusachi, Chiyoko Henmi, and Kitinosuke Henmi in honor of Dr. Jiro Oye (大江二郎) (1900-1968), professor of mineralogy at Okayama University. The mineral was previously reported as tobermorite-10Å.

Type Locality: Fuka mine, Fuka, Bitchū, Takahashi City, Okayama Prefecture – Japan

Related to tobermorite.