1 Not all adenomas produce excess T-4, and doctors aren't sure what causes some to begin producing too much hormone. 2  Thyroiditis. 3  Sometimes your thyroid gland can become inflamed for unknown reasons. 4  The inflammation can cause excess thyroid hormone stored in the gland to leak into your bloodstream.
Forged steel is an alloy of carbon and iron that is compressed under extreme pressure to make a very hard and strong substance. It has been used for thousands of years to create all types of materials.
Chert is a very hard material that produces a spark when it is struck against steel. The heat from this spark can be used to start fires. A flintlock is an early firearm in which a charge of gunpowder is ignited by a flint hammer striking a metal plate (see photo).