Some of what I have read here leads me to believe that a TIA is a stroke that totally reverses itself and all symptoms go away within 24 hrs. Other postings indicate that if symptoms continue or periodically return, then that is an indication that it was more than just a TIA or that there are continuing problems.
Chalk /ËtÊÉËk/ is a soft, white, porous sedimentary carbonate rock, a form of limestone composed of the mineral calcite. Calcite is calcium carbonate or CaCO 3.It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite shells (coccoliths) shed from micro-organisms called coccolithophores.he most common forms are CaCO 3 (calcium carbonate) and CaO (calcium oxide). Small doses of chalk can also be used as an antacid. Additionally, the small particles of chalk make it a substance ideal for cleaning and polishing.
Clays and Clay Minerals. Clay is the common name for a number of fine-grained, earthy materials that become plastic when wet. Chemically, clays are hydrous aluminium silicates, usually containing minor amounts of impurities such as potassium, sodium, calcium, magnesium, or iron.he most abundant use of clay is in brick making. Granite is made up of quartz, mica and feldspar. As quartz is resistant to chemical weathering, it may be removed only as mineral grains of quartz. Feldspars and micas are susceptible to chemical weathering and break down to form clay minerals.