ERIONITE or OFFRETITE, ROCK ISLAND DAM, DOUGLAS COUNTY, WA
Colorless, usually straight, bundles of intergrown crystals forming circular or oval rods with flat ends. Commonly associated with Heulandite and Phillipsite. Frequently with small balls and aggregates of a unidentified mainerals growing on the sides or, espcecially, the ends.
4-2-86 No. 49 5KV APER200 x5350 by CMN
THIS TABLE LOOKS BEST WHEN VIEWED USING INTERNET EXPLORER.
MAGNIFICATION FIGURES ARE FOR THE ORIGINAL SEMs, NOT FOR THE IMAGES YOU SEE ON YOUR COMPUTER SCREEN. I WILL BE ADDING SCALE BARS WHEN I HAVE TIME TO DO THE CALCULATIONS.
Erionite or offretite
Colorless. Bundle termination.
4-9-86 No. 53 5KV APER200 c. x196 by CMN
Rods of erionite or offretite
Colorless. Radial clusters of rods in cavities coated with a bluish clay mineral. Details of the rods can be seen in the next two SEMs.
4-9-86 No. 55 5KV APER200 c x980 by CMN
Erionite or offretite
Colorless. Detail of a single rod showing the bundling of micro-rods and the preferential seeding of unidentified globular mineral on the terminations of these micro-rods.
4-9-86 No. 54 5KV APER200 x1960 by CMN
Erionite of offretite
Colorless. Detail of the termination of a single large rod.
4-9-86 No. 56 5KV APER200 x980 by CMN
Erionite or offretite
Colorless. Detail of termination showing highly regular bundling of crystals giving the rod a slightly star-shaped cross section. Secondary minerals occur on rods of this kind at a much lower frequency.
5-21-86 No. 113 5KV APER200 x500 by CMN
Erionite or offretite
Colorless. Slightly divergent spray of rods covered with balls and terminal coatings of unidentified minerals. In this case, the terminal coatings that have shrunk and cracked indicating they may be a clay mineral.
