OKENITE
Okenite is a hydrous calcium silicate mineral (CaSi2O5·2H2O;
a.k.a. Ca10Si18O46·18H2O).
Though scarce, it is easy to identify. First of all, it's only known in
cavities in some basalt lava flows. It forms whitish-colored tufts or
"cottonballs" of radiating acicular (needle-shaped) to fibrous
crystals. Individual crystals (needles) are flexible and yet quite
fragile. It has a nonmetallic luster, typically white color, white
streak, and is moderately hard (H = 4.5 to 5).
Okenite
(white masses of radiating, slender crystals) partially filling cavity in
basalt (Deccan Traps Flood Basalt, uppermost Cretaceous) from India.
(Dwyer Mercer County District Library # 105-40,
Celina, Ohio, USA)