Tungsten, also known as wolfram, is a chemical element with symbol W and atomic number 74. As a hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds.
The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all the elements. Also remarkable is its high density of 19.3 times that of water, comparable to that of uranium and gold, and much higher (about 1.7 times) than that of lead. Polycrystalline tungsten is an intrinsically brittle and hard material due to its weak grain boundaries, making it difficult to work. However, pure single-crystalline tungsten is more ductile, and can be cut with a hard-steel hacksaw.