Read the text about Zhamanshin crater. Why, your opinion, tektites are also called irgizites?

The Earth's surface has numerous testimonies to extraterrestrial bodies hitting its surface. They are called impact craters, The Earth Impact Database contains a list of 190 impact craters. One of them is the Zhamanshin crater in Irgiz, Kazakhstan.
About one million years ago, a gigantic meteorite exploded here and formed a crater700 m deep and 14 km wide.
The energy released by the explosion was equivalent to tens of thousands of megaton bombs, and temperatures in the region reached several thousand degrees centigrade. Zhamanshin meteor crater is a unique phenomenon among
impact craters because of the tektites, or irgizites, which have
been found here. помогите срочно. ​