METHODS: All rock processing equipment was carefully cleaned between samples to prevent cross contamination. This included washing with warm soapy water followed by a copious water rinse, drying with paper towels and finally wiping down with methanol-impregnated Kim-wipes in the case of rhodamine. Steel parts were lightly oiled with WD40 for storage. The samples for rhodamine analysis were crushed in a Platner mill and further ground in a mortar and pestle until the material passed through a 60-mesh screen. 1.5 grams of each sample was transferred to a 15-cc falcon tube and 4 ml of HPLC-grade methanol added. The samples were then tightly sealed and shaken for 24 hrs at 50 RPM on an orbital shaker. The tubes were anchored horizontally to encourage the slurry to slosh back and forth and thus to stay in suspension. After extraction, the tubes were centrifuged at 2,500 RPM (figure out xg) and the liquid phase transferred to a 5 cc syringe and filtered through 0.2 µm acrodisc (mfgr.) syringe filters directly into 3 ml methacrylate spectrophotometer cuvettes. The Fluorescence was read on a ------------- fluorimeter set to excite at 530 nm and to read fluorescence at 555 nm. Samples were read three times and a mean taken. A standard curve was made of rhodamine over the range of 0 to 100 ppb with linear detection between 0.0125 PPB and 5 PPB. When apparent values of extracted samples produced readings of near the upper limit of the linear range (50 fluorimeter units) the samples were diluted and re-read. Samples for microspheres were first pounded lightly with a small hammer to produce small chips. These chips were then screened through a number 14 screen with the chips thus excluded rejected. Next the sample was passed over a number 100 screen and the fines that passed through were also rejected. The remaining particles were of a known size range (----). 0.25 g of these screenings were placed in a 15 cc falcon tube with 2.0 ml of 100 mM Na pyrophospate (Sigma) and vortexed on high for 30 seconds. 25 µl aliquots were placed on a glass microscope slide and covered with a 25 mm cover slip. Spheres were counted at 200 x under UV illumination on an Olympus XXXXXXX microscope using the purple (get details) filter. If the suspension had more than ca. 20 spheres per field on 200 X, the samples were diluted such that 3 - 5 spheres per field were noted. As controls to verify that the spheres were not preferentially adhering to the inside of the ziplock storage bags or the falcon tubes leading to undercounts, these surfaces were swabbed with a cotton swab wetted with 100 mM pyrophospate and swirled into the bottom of 15 cc falcon tube with 1 ml of the same pyrophosphate solution and 25 ml of this solution was then counted as an actual sample. Few, if any spheres were thus noted.

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