[Illustration: A
Gem-quality celestite crystals from Travis County, Texas. Twice natural
size. Lower portion of the crystals is colorless; the tips are dark
blue.]
[Illustration: B
Opalized wood from the Texas Gulf Coastal Plain. Specimen at left is
rich brown and tan; specimen at right is fossil palm wood and is black,
reddish brown, and white. One-third natural size.]