In her book Reading Russian Fortunes (Cambridge University Press, 1998), Faith Wigzell refers (p.33) to a type of fortune-telling card deck that reached Russia in 1850, ascribed to Marie Anne Lenormand (often called Mademoiselle Lenormand).
These symbolic cards had no numerical values or suits, but divided each picture into four triangles
She then refers to a deck of this kind that was published in the United States in 1992 by Svetlana Touchkoff under the name of "Russian Gypsy Fortune-Telling Cards", which are for sale online. Touchkoff's cards are square, each one is divided into four congruent isosceles right-angled triangles, and on each card the triangles are of four different colours. Each of these triangles constitutes half of an image. When the cards are "spread", significance is given when two triangles, each on a different card, are juxtaposed so as to form a complete image.
Note that these are not the same as at least most of the "Lenormand" cards available today, which are numbered and oblong, and which often contain smaller images of "standard" cards complete with suits and pips. Note too that it is not entirely clear whether the division of images on Touchkoff's cards is similar to what it was on the cards that Wigzell describes, because that would depend on what Wigzell means by the word "picture". If we consider that each card contains a single "picture", then it is indeed divided into four, but for the purposes of divination each of the cards contains not a quarter but a half of a picture.
What I am interested in is the origin of a very particular feature of a deck of fortune-telling cards, namely the use of square cards divided into four triangles in this way.