L. You did not see your brother, when you got the telegram the other day, saying he was ill, May; but you cried for him; and played no croquet. But we cannot talk of these things now; and what is more, you must let me talk straight on, for a little while; and ask no questions till I've done: for we branch ("exfoliate," I should say, mineralogically) always into something else,--though that's my fault more than yours; but I must go straight on now. You have got a distinct notion, I hope, of leaf- crystals; and you see the sort of look they have: you can easily remember that "folium" is Latin for a leaf, and that the separate flakes of mica, or any other such stones, are called "folia;" but, because mica is the most characteristic of these stones, other things that are like it in structure are called "micas;" thus we have Uran-mica, which is the green leaf I showed you; and Copper- mica, which is another like it, made chiefly of copper; and this foliated iron is called "micaceous iron." You have then these two great orders, Needle-crystals, made (probably) of grains in rows; and Leaf-crystals, made (probably) of needles interwoven; now, lastly, there are crystals of a third order, in heaps, or knots, or masses, which may be made either of leaves laid one upon another, or of needles bound like Roman fasces; and mica itself, when it is well crystallized, puts itself into such masses, as if to show us how others are made. Here is a brown six-sided crystal, quite as beautifully chiseled at the sides as any castle tower; but you see it is entirely built of folia of mica, one laid above another, which break away the moment I touch the edge with my knife. Now, here is another hexagonal tower, of just the same size and color, which I want you to compare with the mica carefully; but as I cannot wait for you to do it just now, I must tell you quickly what main differences to look for. First, you will feel it far heavier than the mica. Then, though its surface looks quite micaceous in the folia of it when you try them with the knife, you will find you cannot break them away-- KATHLEEN. May I try? L. Yes, you mistrusting Katie. Here's my strong knife for you. (Experimental pause. KATHLEEN doing her best.) You'll have that knife shutting on your finger presently, Kate; and I don't know a girl who would like less to have her hand tied up for a week. KATHLEEN (who also does not like to be beaten--giving up the knife despondently.). What CAN the nasty hard thing be? L. It is nothing but indurated clay, Kate: very hard set certainly, yet not so hard as it might be. If it were thoroughly well crystallized, you would see none of those micaceous fractures; and the stone would be quite red and clear, all through. KATHLEEN. Oh, cannot you show us one? L. Egypt can, if you ask her; she has a beautiful one in the clasp of her favorite bracelet. KATHLEEN. Why, that's a ruby! L. Well, so is that thing you've been scratching at.