Instrument data from three buoys in Lake Superior provide a reliable record of water temperatures since about 1980, and the information also shows that, with water temperatures running in the mid-to-upper 60s (and even warmer closer to shore), âwe are at record temperatures for this time of year,â according to Austin.
The talc is formed by the alteration of sedimentary magnesium carbonate rocks (dolomite and magnesite) at elevated temperature and pressure below the earth's surface. While the magnesium is fixed in situ, the silica is transported by silica-containing hot fluids to react with the Magnesium- bearing carbonates to form talc. These altered rocks are then talc-rich dolomites or magnesites. This type of deposits usually deliver the massive talcs accompanied by carbonates, chlorite and some quartz.
In nature talc does not exist in itsâ theoretical form or purity, but a small fraction of Mg and Si atoms can be replaced by iron (Fe), aluminium (Al) or nickel (Ni). Typically, the colour of talc stones is pale green or white, but the colour can vary from pinkish to dark green. The surface of talc stone has slippery feeling and pearly lustre. The unique fine structure of talc makes it ideal filler for protective coatings: Talcâs surface is electrically neutral, which makes talc highly hydrophobic, thus water.repellent. Talcâs particle form is platy, which is important for an optimum filler packing in the paint film. The platy particles also create a.good.barrier against