Aquamarine is the blue variety of the gemstone beryl, which comes in a number of different colors [Green is emeralds, golden is heliodor, colorless is goshenite, pink is morganite, and red is, well, red beryl]. The coloration differences are caused by impurities within the beryl.

Aquamarine is probably the most common, and can be found in most beryl-bearing localities. That isn't to say that it's all over the place, but it's a fairly accessible gemstone to buy. Crystals from Brazil and Pakistan are usually inexpensive, although one must be aware that they have often been irradiated to enhance the blue coloration.

Today's mineral is Okenite, those ever-popular fuzzy white cottonball minerals. Named after the German naturalist Lorenz Oken, they were first discovered in Greenland in 1828.

It is important to note that natural Okenite is WHITE. If you see it in other colors, it has been dyed. The white crystals do not have good contrast with the white matrix, and many sellers use food coloring to make a more colorful specimen, which they then try to pass off as natural. You'll often see it dyed orange, blue, or green.

Okenite is usually associated with zeolites, and is generally found inside basalt geodes. The 'hairs' are somewhat flexible, but still very fragile.

In my days of doing mineral shows, I found that putting a sign saying "Fragile - do not touch" did not deter every passer by from jamming their finger into my okenites. When I got fed up with smashed and mangled specimens, I put up a different sign that said, "Danger! Sharp needles!". Problem solved. However, they are actually quite soft and harmless to touch, just be very gentle with them.

Most of the Okenite currently in the market comes out of India, particularly Maharashtra Province.

Celestite, also called Celestine, is a clear to blueish gray mineral, with crystals which often resemble those of Barite [though Celestite is much less common]. The name comes from the Latin 'caelestis', meaning 'heaven or 'sky' - a reference to the beautiful blue color some of the specimens can display.

Currently, much of the specimen-worthy supply comes from Madagascar, including the one shown above. But although Celestite is a popular mineral for collectors, for obvious reasons, it has other important uses as well. It is the only commercially mined source of strontium carbonate and other strontium compounds, which are used in pyrotechnics, television tubes, and even toothpaste for sensitive teeth.

Have you ever woken up on a cold morning, and admired the intricate, delicate ice crystals that grew on your windowpanes overnight?

You may not have known that you were witnessing the growth of a mineral, right in front of your very eyes. The definition of a mineral is "a naturally occurring inorganic substance with a definite chemical composition and a regular internal structure."

Liquid water is not a mineral, since it has no crystal structure, but when it freezes, it becomes crystalline. However, the definition includes "naturally-occurring" - so, technically, the ice in your freezer is not a mineral, but what you scrape of your car windshield in the morning is.

​First discovered in Mexico in 1801, vanadinite has long been a popular mineral among collectors due to its spectacular red-orange coloration and hexagonal crystals.

Vanadinite is one of the primary ores for the element vanadium [and is also sometimes used as a source for lead]. Vanadium is frequently used as an additive to strengthen steel, with a wide range of industrial applications, so it is in much demand.

Vanadinite is what is known as a "secondary mineral", which means it forms from a pre-existing material - in this case, by the oxidation of lead-bearing rocks.

Please remember that this stone is a lead ore, and all lead ores should be treated with caution. Keep away from young children, and always wash your hands after handling them.