This is a stylish-looking word, I’d say, one ready for TV: it has the play of the narrow ti and wide za, the rectilinear t and the diagonal z, the neat line across on the first three letters with the dot of the i hovering above it, the first three letters like the styling on the side of a convertible tiz and at the end a soft curly a. It brings to mind Liza as in Minnelli, and also (for those who know this) Tisa as in the sister of Mia Farrow. For me it also brings to mind my sister-in-law Tisa, whose name I sometimes pronounce to rhyme with Liza.
This word is actually pronounced like “tee-za”. And what does it mean? Oh, think of all the things you might want to give a name such as this. Where has it been all your life? The iza ending makes me think of Spanish words (indeed, there is a Mexican Spanish word tiza for a sort of chalk; that word comes from Nahuatl), or just maybe Italian (a double z would be more like that). It really is a little gem, a precious little stone – you could quite fairly call it lapidary.
And what it names is a mineral. The Oxford English Dictionary has an almost startlingly recondite definition: “Ulexite or hayesine.” Um. OK. What are those?
There’s a first hint in the etymology. Its source is Quechua (the language of the Incas): t’isa “card wool” (verb), which is a reference to its appearance. So it’s like wool fibres? Rather. Ulexite is the more common name; it comes from the German chemist Georg Ludwig Ulex. Hayesine is more problematic; what it refers to in a given instance may be ulexite. Anyway, the rocks look the same.
How do they look? Like a translucent white fibrous mineral. And those fibres, which are all oriented in the same direction, give tiza a particular optical property, as they act as optical fibres. If you cut a slab of tiza (ulexite) across the fibres and put something up against one side, the other face will display an image (not necessarily sharp and clear) of what is against the one face, regardless of the angle you view it from. So if you put a bright object perhaps 3 cm from the bottom, then on the other side you will see the indistinct image of that thing 3 cm from the bottom – even if you’re looking at an oblique angle from above.
This property gives it a nickname: TV rock. ’Tis a good name – TV is similar in ways to tiza. Unfortunately, it seems that tiza is not ready for prime time; ulexite is the more common name, and tiza the more recondite, ironically. Such a shame to make so little use of such a good name.