The green stone
Malachite is a green mineral made of copper carbonate. Cut and polished, it shows bands of light and dark green. Its name goes back to the Greek words for a "mallow-green stone", because its color reminded people of mallow leaves. Big deposits have been mined in the Ural Mountains of Russia and in the Democratic Republic of the Congo, as the Wikipedia article on malachite explains.
From paint to palace walls
Ground malachite was used as a green paint pigment from ancient times until about 1800. In the Hermitage Museum in St. Petersburg, a whole hall called the Malachite Room is decorated with the stone. The ancient Egyptians spoke of the afterlife as the "Field of Malachite".
Where the code comes from
The code #0BDA51 matches the malachite green in Maerz and Paul's A Dictionary of Color of 1930. On a screen it is much brighter than most real stones, which are darker and more bluish. Don't confuse it with malachite green the dye. That is a man-made chemical named for its color, and it contains no malachite. For other gem greens, see emerald and jade.

