The extraction process to remove the lead from the sulfur is very simple, thus lead has been extracted from Galena since the earliest times.Galena from certain regions is rich in silver, and some specimens may contain as much as 20 percent silver. Because of this, silver-rich Galena is also an ore of silver.
Being exposed to sunshine will also increase your levels of vitamin D. Hiking is a cardiovascular activity, depending on how hard you push yourself during a hike, and thus has benefits for your cardiovascular system, such as reducing the chances of heart disease, and increasing your overall fitness.
What is Average? Hikers will vary in their conditioning, weight of gear, natural fitness, comfort range, and several other factors that influence hiking speed. With all these considered, most hikers will average about 2-3 miles per hour (3.2-4.8 km/h). Besides personal differences, different trails will have a huge impact on your hiking speed. Some trails are at a higher elevation, which decreases the amount of oxygen replenishing your muscles.