View Full Version : Question about calcite

21-04-2007, 15:48
I have a very pretty orange calcite sphere but hesitate to keep it out because calcite is such a soft stone. I'm worried that even dust might damage the stone. In going through the pics folks have posted, it looks like some of you have calcite. How do you feel about keeping it out? Is it holding up well?

Thanks for your help.

Little Hare
21-04-2007, 15:58
well i have a golden calcite crystal ball and i have it out on my dresser 24/7 and its holding up fine... my opinion is stones are meant to be used

21-04-2007, 16:31
Well now if it was something like peach selenite I'd keep it under cover, you can scratch that stuff with rough skin on your fingertips.

But calcite is a lot tougher than you might realize. I've got calcites of all known colors and in all shapes and forms that have been kicking around the house for 30 years or more and taken quite a beating and there's nary a scratch on any of them. The pink calcite (mangano) is the most susceptible to scratches but even the pink would need to be deliberately gouged with something sharp to get a good scratch showing on it.

This following information might help you understand better about hardness of stones, it explains about the current REVISED mohs tests:


quoted from http://www.galleries.com/minerals/hardness.htm

" ......... Below is a revised Mohs Hardness Scale with some everyday items listed:

--fingernail at 2.5
--copper (old penny) at 3.5
--window glass or typical knife blade at under 5.5
--streak plate or good steel file at over 6.5
Again, the Mohs Hardness Scale is only relative. Meaning that fluorite at 4 is not twice as hard as gypsum at 2; nor is the difference between calcite and fluorite similar to the difference between corundum and diamond. An absolute hardness scale looks a little different than the relative scale. Using sensitive equipment, a comparison of the absolute hardness of minerals can be measured. It turns out that most minerals are close in hardness. But as hardness increases, the difference in hardness greatly increases as seen in the scale below.

Below is an absolute hardness scale:

1 Talc
3 Gypsum
9 Calcite
21 Fluorite
48 Apatite
72 Orthoclase
100 Quartz
200 Topaz
400 Corundum
1600 Diamond
The simpler, relative Mohs hardness scale is much easier to remember and use.

It is easy to see why diamond gets so much respect as the hardest natural substance know to man. The next hardest mineral, corundum, is four times softer! There are many substances that are currently being created and studied to beat diamond in hardness. But diamond's all carbon, extremely dense, structurally sound and tightly bonded structure is hard to beat. At present only diamonds created with isotopes of carbon have exceeded the mark of 10 on the hardness scale............"

28-04-2007, 11:03
Thanks very much for your replies. The absolute hardness scale is really interesting and most useful. Based on your experience, I'll get my calcite sphere out of it's box and put it on display. Thanks again.

29-04-2007, 01:24
I dont know very much about crystals (i'd like to!), but I know a little about geology and chemistry-

Be sure to keep anything with an acidic property away from your calcite, it's pretty basic. If a little bit of an acidic substance stays on the surface, it might pit slightly.

if you skin runs a little acidic rather than basic, just use clean hands to handle to the stone. ^_^

Our geo lab had some pieces of calcite that survived repeated scratch tests, acid tests, licking, nibbling, dropping, handling and all kinds of general exploration in the name of curiosity.

03-05-2007, 15:04
I can only wonder about lab tests that included licking and nibbling. You must work in a most intersting place. I will try not to gnaw too hard on my sphere, lol.