Kathleen Boyd, age 12, of Fairburn, Ga., or her question:

What is mica?

The name mica, which means glittering, is given to a. whole family of amazing minerals. Most of the large slabs of mica are buried among the hard rocks of the earths crust. But you map be lucky enough to find it peeping through the surface rocks in the Appalachian mountains and in certain regions among the Rockies. You may catch sight of it from afar glinting in the sunlight like a lost cache of jewels.

Your discovery may be a shiny, flat slab of a mineral that reminds you of water. It may be clears, as pure spring water tinted some shade,, or brown like muddy creek water or black as the water you see when you look down into a deep well, As you hold it in your hand, you may also think of a book. For slab mica is pressed together in the thinnest of of leaves, A slab one inch thick can be separated into about a thousand pages,

The thinner a slab of mica is sliced, the clearer it becomes, If you pull the layers apart carefully, you soon have a pile of material which seems suitable for making fairy window panes. The fine sheets are strong and pliable and they refuse to melt, even when close to a hot furnace.

You will most likely fall in love with your piece of fascinating slab mica and give it a place of honor in your rock collection. Actually, it should have a, whole family of rocky companions along with it. So now let's look for other forms of mica, for it is quite plentiful in the earth's crust.

It often occurs in small, bright flakes mixed wt th some of the drab rocks. Sometimes you find a lump of hard, grey gneiss which looks as though  it had been mixed with a generous helping of shiny salt and pepper. This seasoning is actually small flakes of mica, It also occurs in granites, looking somewhat like a sprinkling of captured star dust„ It occurs, often like grains of sparkling white sugar, through pink and lavender lumps of lepidolite, which is an ore of the metal lithium: Mica also comes in pale yellow, honey color sad deep amber,

Some forms are deep rose, some are green and some pearly grey,, The mineral mica is a very complex compound of silica and aluminium. Lithium, iron, magnesium, iron or potassium may be present as impurities. Traces of these ingredients give various tints end qualities to the basic mineral. The large sheets of mica are actually crystals of the mineral. The slabs are six‑sided, often several feet wide and weighing 100 pounds. This slab mica is formed in the heat of volcanic lava. Some of the flake mica may be formed as metamorphic rocks are crushed and treated by movements in the earths crust,

The fairies may well use mica for window panes, we do not know for sure, But the Moscow of old Russia certainly used it as window glass. Our ancestors used it as stove and oven doors and it is still used for this purpose in many industrial furnaces, Plake mica is used as artificial snow to add that fairy sparkle to our Christmas trees,