Display Lighting of Minerals
By John Betts John Betts - Fine Minerals

The subject of displaying and illuminating minerals comes up all of the time. Every collector understands that there is no sense in collecting objects of beauty, like minerals, if they cannot display and share their appreciation with others.

Every collector comes up with their own solution for storing and displaying minerals. Whether it is old IBM card file drawers or nice glass-front shelving from IKEA or perhaps a custom-built display cabinet built precisely to the owners home. Some collectors like drawers, others like display cases, other like combinations. There is no one answer. It is up to the individuals tastes and budget on how to solve the display problem.

But the most collectors do not have the knowledge to make decisions about how to illuminate their displays once they have them. A collection displayed in a poorly lit basement or garage is just one step above storing minerals in cardboard boxes. You are not really "seeing" the minerals. This article will present basic lighting considerations and solutions that are unique to mineral collectors.


Every collector thinks the first consideration of display lighting is color temperature. This is wrong. Color temperature is important to photography, but is a secondary consideration to displays. The next section will discuss color , color temperature, and light types.

The first consideration is the type of coverage and distribution. Every exhibit or window display designer uses light-selection as the primary tool to enhance the objects on display. Options available are diffuse overhead panels, back-lighting light boxes, linear fluorescent tubes, compact fluorescent bulbs, incandescent bulbs, and halogens. The primary concern is the size of the light source. If a mineral is illuminated with a broad, diffuse panel it will appear dead and lifeless. If the same crystallized specimen is displayed under several small point sources of light it will sparkle and come to life.

This is because each point source will create a reflection. The more points of light, the more sparkles. Of course there is a practical limit, too many point sources will start to merge and have the reverse effect. The effect of point sources of light can be seen in every jewelry store. Look at the store’s lighting. In the ceiling will be an array of small point sources of light, generally halogen lights. Each light source will reflect and refract off the gemstones and give it that brilliance that we love from gems. To see the difference, take a diamond from the store outside to a shaded area. Now the light will be coming from the diffuse light of open sky and will look dead.

The same effect is used by mineral photographers. A good photograph will carefully illuminate the crystal faces so that each face is differentiated from adjacent faces. To do this, several light sources and small reflectors will be used. See Jeff Scovil’s excellent book on mineral photography to see what a finished setup looks like - very elaborate. Most times photographers will not use the standard photographer’s tools of reflecting umbrellas or broad diffusers because these have the effect we discussed, of dulling the mineral and not describing all of the faces.

It is a sad reality though, a mineral display case can never achieve the beauty of a single mineral photograph. The mineral photograph has all lights optimized for that one specimen viewed from a single point of view (often a very slight shift of camera position can upset all of the light arrangements). Your display case though does not have just one mineral and can be viewed from many eye levels and vantage points. So it is important to recognize that limitation. However the display has something that the photograph will never have - you can pick up the specimens. The lighting therefore should be optimized for general viewing and for the handling of the specimens.

There are minerals that do not have crystal faces, like botryoidal prehnite, that do look better under diffuse illumination. And there are minerals like agate slabs or ametrine crystals that look better when back-lit from a light box. These minerals should be separated and displayed separately under optimum conditions for them.


We have learned lesson one - that several small point sources of light will make a crystal sparkle. Do not forget that. It is the single most important rule of illuminating minerals. So what type of bulb should you use to create point sources of light?

It is obvious that fluorescent bulbs are either too long or too big to create small point sources. The same is pretty much true of ordinary incandescent bulbs, especially in the wattages required to illuminate a display case.

The simple answer is quartz halogen. The most useful is the MR-11 bulb which has a built-in dichroic reflector to focus the light forward. There is a larger bulb with built-in reflector, the MR-16, but it is too big unless you are going to mount the lights in the ceiling or more than four feet from the minerals. Both MR-11 and MR-16 are available with different dispersions from flood to spot to narrow spot. This is the other reason why MR-11 are a good solution for minerals.


We have narrowed our selection down to MR-11 quartz halogen bulbs (or MR-16 if the bulbs are going to further away). Now what about color temperature?

This is very important to photographers because film is very intolerant of the color temperature or the "color of the light". It is another reason that fluorescent and incandescent bulbs are not good solutions (although they are improving). But even MR-11 halogen bulbs are not perfect. They have an overabundance of yellow-orange and lack some blue-violet. They are still better than the alternatives. As a result wulfenite will look super, but azurite will not be perfect. The azurite will still look better under MR-11 halogen than all other bulbs. Except one.

These are the new neodymium light bulbs available under trade names Chromalux and Verilux. These are rare-earth glass bulbs that filter out the excess yellow-orange and balance the light down to equal the blue-violets. In a side by side comparison these bulbs look pinkish, but that is from the additional proportion of blue-violet.

Neodymium bulbs are available in many styles. The good news for mineral displays is they are available in MR-16 halogen versions. Unfortunately only in the flood-type dispersion. The bad news is they are not cheap. Expect to pay $16-20 per bulb. But if you have hundreds of dollars worth of minerals, you should not skimp on your lighting.

Having said all this, it is my recommendation that the extra expense and limited bulb selection of Neodymium lights are not critical to mineral display unless your collection is overwhelmingly azurite or pseudomalachite. Using the smaller MR-11 halogen bulbs, selecting the proper dispersion for your needs, will be best for most mineral displays.


The bulb wattage and the amount of heat they put out are directly related so they will be discussed together. MR-11 bulbs are available in several wattages, 20, 35, and 50 watts. The 20 watt is more than adequate if your mineral will not be more that three feet away from the bulbs. The 20 watt versions are also more readily available.

The beauty of halogen bulbs is they are so efficient that a smaller proportion of the energy is wasted generating heat. But they are hot. You should provide venting at the top of any enclosed display or use a glass top with the lights mounted above the glass or use a light fixture that is recessed in the case top with most of it above and outside the display case.

If you have heat sensitive minerals place them low in the display case, away from the heat at the top. Also your lighting should be optimized so that you only have the minimum number of lights required to illuminate the mineral. Nothing wasted.

If heat is a big concern because of the specific mineral you collect, there is an option fiber optics. A new lighting system was developed for museum display that uses a central, bright halogen source that is light-piped to fixtures to illuminate the display. It is available from NoUVIR Research. It is expensive, as you can imagine the cost of all of the fiber optics. But as the name implies there is no UV or IR (heat) from the lights. And the fixtures give you incredible control of the dispersion and aiming of the light. And, important to mineral displays, they produces point sources of light. The recent "Nature of Diamonds" exhibition at the American Museum of Natural History in New York City used these lights and the results were dramatic. But unless you are a museum or have a multi-million dollar collection they are not necessary.


We have narrowed our needs to MR-11 20 watt quartz halogen bulbs. What type of fixture should you use? MR-11 bulb are low voltage. They require the 120 volt house current to be stepped down to 12 volts. There are versions of quartz halogen bulbs that screw into regular medium base light sockets and use 120 volts. These have small internal transformers built-in. But you are buying a transformer for every bulb. Each bulb costs about $16. It is cheaper to have central transformer and keep the bulbs cheap (a low-voltage MR-11will cost $10).

There are two types of fixture and transformer arrangements. The most complicated is a central transformer connected to house voltage with low voltage wiring running to the fixtures. The more convenient is a fixture with built-in transformer. The latter is easier to connect, but if you understand wiring the former is more flexible.

As a display designer my advice to most mineral collectors is to buy a low voltage track lighting system. This allows maximum flexibility in arranging and rearranging the lighting as your needs evolve with the convenience of little wiring to deal with (the track is the wiring). Additionally, there is a wide selection of minimal light fixtures that accept MR-11 halogen bulbs. The brands of fixture are too numerous to name, almost every manufacturer makes a version. Your best choice is to visit your local lighting store. They will have many available for you to review and select the right one for your display case.

When looking at track systems think creatively about how you will use and mount them in your display case. They do not have to be mounted on the cabinet top. You can run two tracks down each side if you have a tall case. There is no limit to where you can mount them.


Following are some typical complete solutions to common display case problems.

Vertical Display with glass shelves - Glass shelves help in illuminating the case because the light goes farther. I would start by mounting three or four MR-11 narrow-spot halogens in fixtures flush to the cabinet top. The fixture will stand proud of the case top and will require a plinth or something else to hide them.

The top lights will be adequate to illuminate the first two shelves of minerals. But if the case is very tall, and you have the shelves densely packed, additional lights will be needed. I suggest a track be mounted down each side close to the front of the case. Use one fixture per shelf on each side with an MR-11 flood halogen. The fixture should be positioned just under the shelf above and aimed down and towards the center.

Finally I would consider placing a mirror in the bottom to reflect back up some of the light coming down. This will prevent the bottom shelf from looking dead.

Barrister-type cases with wood shelves - Opaque shelves prevent any lights on shelves above from contributing to the illumination to the shelf below. Therefore each shelf must be completely self-contained for lighting. Again I would use a low-voltage track mounted across the front edge on the underside of the top and shelves. Use three to four fixture with MR-11 flood halogens to illuminate each shelf. Beware of heat in this installation. You can reduce the lights needed by mounting a mirror on the back surface to reflect back forward the lights.

Small shallow glass display cases - These are often reused watch or jewelry display cases. Here three or four MR-11 flood halogens mounted above and slightly overhanging the front will work well. You can use a track and mount it too a brass support /shade that a local metal shop can create for you (you can even find an off-the-shelf fixture if you look hard).

Wall of Glass-Front Cases with glass shelves - Again I would start with MR-11 narrow-spot halogen mounted in the top surface aiming down. They should be spaced about one fixture every 16 inches. To Illuminate the "wall" of displays I would use a track mounted to the ceiling three feet in front to the cases. Use MR-16 spot 50 or 75 watt halogens (Chromalux if you can afford them) spaced every two feet along the track.

In all cases, lighting designs should be flexible to allow you to make adjustments, add or subtract fixtures, and refine as you go. It is impossible to create a single design for all installations. There are too many variations. But these suggested solutions are good places to start.


Remember that the lighting must illuminate and enhance the collection. Bad lighting and cheap shortcuts will make a great specimen look bad. Before you start your lighting project, look at your display. Let’s say you have 50 specimens averaging $100 per specimen (at today’s prices) - that is $5,000. You should not give it a $25 lighting system. Spend an amount that is proportionate to the value of your display and consider your lighting design as part of the collection.

Every night as we have a family dinner my seat faces my mineral display cases. I sit there and take in the beauty of all that I have collected. Occasionally I will bring my daughter over after dinner and we talk about her favorites or pull out a special one to look at closely. The lighting design enhances these experiences. The time and expense of installing a good lighting design is worth every penny spent.


You can order and get technical information on Chromalux bulbs at: http://www.blanksfab.com/chrome.htm

or contact

Lumiram Electric Corporation in Mamaroneck, NY 10543
NoUVIR Research
U.S. Highway 13 & Loop 532
RR 4 Box 748
Seaford, DE 19973
PH. 302-628-9933 Fax 302-628-9932


Mr. Betts has worked for twenty years as a design consultant to museums and corporations. His training and work in exhibit design and product design has encompassed everything from exhibits for the Museum of Science and Industry in Chicago to camera and imaging product designs for Polaroid and most recently Eastman Kodak. His second hobby (if you consider minerals his first) is large and medium format fine art photography, the result of this skill is evident in his mineral photographs on his web site.

For permission to reprint and to read other articles authored by John Betts, visit John Betts - Fine Minerals.

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