Go to a hardware store and get the size bit you need that is made for metal. Most cast iron isn't really hard unless it is white cast iron. If the hole is over 3/16, pre-drill it with a small bit first. It might be a good idea to use some cutting oil to.
For more info, see the section on calcium absorption. High calcium foods include dark leafy greens, cheese, low-fat milk and yogurt, bok choy, fortified tofu, okra, broccoli, green beans, almonds, and fish canned with their bones. The daily value (DV) for calcium is 1000mg.
The element is not found free in nature, but occurs as orthoboric acid usually found in certain volcanic spring waters and as borates in boron and colemantie. Important sources of boron are ore rasorite (kernite) and tincal (borax ore).Both of these ores are found in the Mojave Desert.Tincal is the most important source of boron from the Mojave.mportant sources of boron are ore rasorite (kernite) and tincal (borax ore). Both of these ores are found in the Mojave Desert. Tincal is the most important source of boron from the Mojave.