Bluish white metal. Very soft, inelastic and easily fusible .
In nature, thallium is found in the Earth's crust, 0.7 ppm, in minerals such as crookesite, lorandite and hutchinsonite . The isotopes found in nature are 203Th (29.50 %, stable) and 205Th (70.50 %, stable) .
In pure solid form, thallium exist in a hexagonal close-packed structure .