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These minerals may include malachite, tigereye, rose quartz, amethyst, onyx, bloodstone, and rhodenite, among others.Alabaster marbles are made from real marble and originate primarily from the Berchtesgaden-Salzburg region of Germany, where they were made chiefly after around 1790.Therefore, after 1813 agate workers began heating the agates in ovens to achieve the same effect.

Agates were made by first chipping small cubes of stone from a larger piece of material.

Then, the stone was ground down by workers who had to lie on their stomachs across a sloping board, with their feet braced against pieces of wood attached firmly to the floor.

However, following this procedure they were placed into polishing drums, and depending upon the amount of time they spent in these drums the facets could be completely removed, or might remain mostly intact.

Machine ground agates, on the other hand, never have facets, though this too cannot be used as a trait to date agates.

Many of these marbles were shipped to the United States during this period.

After the great war, the industry was seriously crippled, not only because of the war but likely resulting from the growing popularity of machine made glass marbles, which were initially given names to suggest their similarity to "aggies." Hence, such companies as Akro Agate and Christensen Agate.

This position allowed the workers to face the millstone and exert the considerable force needed to grind the stone.

The millstone itself was made of sandstone and measured around five feet in diameter.

Soon thereafter, the workers realized that a reddish color could also be achieved by immersing the marbles in iron nitrate or iron vitriol solutions.

The black color in some agates was effected by boiling that agate in a sugar solution or soaking it in honey, and then treating it with sulfuric acid.

There are many other types of semiprecious stone that can be placed in the agate category.

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