Cleavage. The way in which a mineral breaks along smooth flat planes is called cleavage.

Definitions. Cleavage – The tendency of a mineral to break along flat planar surfaces as determined by the structure of its crystal lattice. These two-dimensional surfaces are known as cleavage planes and are caused by the alignment of weaker bonds between atoms in the crystal lattice.

A mineral’s appearance helps identify it. However, many minerals occur in more than one color, so you would need to examine other properties as well. You might also notice how the mineral reflects light, which determines how shiny or dull it is. Most minerals reflect light in characteristic ways.

There are two major ways in which minerals break when you give them a hit: (1) they can break irregularly, in which case we say they ‘have fracture’; or (2) they can break along parallel, planar (flat) surfaces, in which case we say they ‘have cleavage’!

Fracture describes how a mineral looks when it breaks apart in an irregular way.

Minerals with a lesser (but still relatively high) degree of lustre are referred to as subadamantine, with some examples being garnet and corundum.

• Dull lustre. Kaolinite.
• Greasy lustre. Moss opal.
• Metallic lustre. Pyrite.
• Pearly lustre. Muscovite.
• Resinous lustre. Amber.
• Silky lustre.
• Submetallic lustre.
• Vitreous lustre.

Calcite

Acid Reactions: Reaction to acids is a property that can be used to help identify some carbonate minerals and zeolites. Dilute hydrochloric acid will react with carbonates such as calcite to give off appreciable bubbles of carbon dioxide in a relatively short period of time.

Carbonate minerals, including calcite and dolomite, are the most common minerals that react to acid.

Carbonate minerals such as calcite tend to fizz or efferves when tested with Hydrochloric Acid (HCl). Non-carbonate minerals, especially silicates will not react to HCl.

calcium carbonate

Among the common minerals, only calcite (or its polymorph, aragonite) react strongly to a dilute solution of cold hydrochloric – HCl – acid.

Quartz is a mineral, and it does not rust. Vinegar does not affect quartz since it is a weak acid, but it can dissolve mineral impurities coating quartz. You can clean quartz with dilute vinegar but be careful not to leave it wet with either vinegar or water for long.

If your quartz crystals are encrusted with calcite, barite, or lime carbonates, you can try cleaning them with ordinary household vinegar and washing ammonia. You’ll want to soak them for 8-12 hours in full-strength vinegar. Wash the crystals well, and then soak them for the same amount of time in washing ammonia.

Add 1/4 cup of bleach and stir. Let the rocks soak for about two days. If stains, dirt or grit still remain on the rocks, apply denture cleaner or a paste made from baking soda and water and scrub them with a toothbrush or small nylon bristle brush.

Some people have reported success in removing organic materials such as lichen, clay minerals ore fine grained minerals from quartz and other minerals with the use of hydrogen peroxide solutions. When the solution reacts with the manganese minerals it generates bubbles of oxygen gas.

How To Clean Rocks

• Hydrogen peroxide – Use to remove manganese stains.
• Citric acid – Use to remove manganese stains.
• Windex (with ammonia) – A good clay deposit remover and final surface cleanup.
• Distilled Water – Use to clean sensitive species and as a final soak after acid treatment.

Shine the crystal with vinegar. Soak one end of a cotton swab in white vinegar and use it to rub down each faceted side of the crystal or clump. Follow each stroke from the wet swab with a stroke from the dry end to remove the excess liquid.

I prefer to dissolve ordinary household baking soda in a bucket of warm water the immerse your specimens in it (after a brief pre-rinse). Let them sit in the baking soda solution for 15 minutes, then proceed with washing. You can fully neutralize your old acid with crushed limestone or marble or with more baking soda.

The acidity of the vinegar will help dissolve excess particles, revealing the tiny crevices of the fossil. Let the fossil soak for about two minutes.

Petoskey Stones in a Rock Tumbler A rock tumbler can be used to smooth rough Petoskey stones.

Unpolished, quality Petoskey stones are available at an average of around $4 per pound. This price is for about 2-5 stones per pound. Some online sites charge up to $10 for a pound of raw, unpolished, small stones–up to seven stones to a pound.

Make sure you only apply to the fossil itself and not the matrix as the idea is highlight the fossil, not what surrounds it. If you find the surface too shiny for your taste, a light buffing with fine steel wool will take the shine off. I also use Krylon matte acrylic spray for a totally flat finish.

A wide variety of other fossils are found but are not amenable to tumbling. The crinoids are abundant, loose or can easily be removed from the limestone matrix. The crinoids are placed in a rotary tumbler with water and tumbled for about two hours, open the barrel and you will see a slurry mix.

Polishing your fossils is not only a way of presenting a fossil so that it’s visually appealing, with all details easily visible. The polishing isn’t difficult, consisting mostly of making successive passes with abrasives to remove scratches and bring a shine to the fossil face.

Here are some ways to care for fossils.

1. Clean fossils before storage. To make preservation easier, fossils should first be cleaned of dirt and residues.
2. Fix broken parts. Because of old age, some fossils may be fragile and have broken and cracked parts.
3. Keep your fossils in a box.
4. Make labels.
5. Regularly remove dust.