Modern Suiseki

Kotaro-ishi

This is just my personal opinion, but I have the impression that Kotaro-ishi are difficult to understand for beginners to suiseki.

Kotaro-ishi are usually large garden stones that are placed outdoors and have weathered, which may be one reason why their characteristics are difficult to convey.

Since large sizes are the norm, Kotaro-ishi of reasonable sizes are rarely available at auctions, making them a type of stone that is difficult to obtain.

Next, the quality of the stone is also difficult to grasp.

Kotaro-ishi are basically poorly sorted deformed conglomerates that are indigo blue in color. Another characteristic is that they have a unique landscape with significant unevenness due to erosion caused by weathering.

The complex stone appearance created by erosion caused by weathering is one of the excellent points of Kotaro-ishi as suiseki, but if weathering becomes excessive, the stone becomes crumbly and the quality of the stone is difficult to grasp.

However, many of the unweathered areas are a vivid indigo-blue color, and some have a luster similar to that of jasper. These areas are smooth to the touch, and when water is poured on them, the color becomes even more vivid. This is another outstanding feature of Kotaro-ishi-ishi.

Kotaro-ishi are mainly indigo blue, but there are also red and black ones. The red parts of red Kotaro stones are more similar to jasper than the indigo blue ones, but I feel that many of them have layered red parts that look like skin.

As mentioned above, the name Kotaro-ishi comes from the name of the Ainu hunter Kawana Kotaro, which is unusual since most Suiseki are named after the river or place where they are found. However, considering that the stream where Kotaro-ishi is found is called Kotaro Sawa, it can also be said that Kotaro-ishi is named after the place where it is found.

Sarugawa-ishi - Blue Kotaro-ishi

This stone was obtained as Sarugawa-ishi, but because of its quality it can be considered Kotaro-ishi that has been worn down by the river, so I will introduce it as Kotaro-ishi.

The stone resembles limestone, sprinkled with white on an indigo-blue background. It is rounded overall due to wear from the river, giving the impression that it is not very hard.

The condition of the scattered white areas at the bottom is even easier to see.

Sarugawa-ishi - Red Kotaro-ishi

This stone is a Kotaro-ishi with a thin blue layer on a red background. The red of Kotaro-ishi is a relatively vivid shade, and many of them show an appearance similar to jasper, such as the way the colors mix.

When viewed from below, you can see undulating blue layers intruding into the red ground.

It looks similar to jasper, but in reality it is not as hard as jasper and feels a little soft, which makes it suitable for viewing as a suiseki. Jasper is one of the hardest stones available in the market, excluding gemstones, but because it is too hard, it does not change shape much and its color is too bright, so it is not suitable for suiseki.

In that respect, Kotaro-ishi is more flexible in shape than jasper and its color is more subdued, making it good for suiseki. Although there seems to be more demand for it as a garden stone than as a suiseki.

Sarugawa-ishi - Blue Kotaro-ishi

This stone is typical of Kotaro-ishi. While the areas rubbed by the river have a smooth surface like jasper, there are also areas that are white and very uneven due to erosion caused by weathering.

The vibrant colors of the stones when wet make them a fun addition to the Suiseki collection. The shape doesn't fall into the typical Suiseki category, but I like it. I like thinking about the angle from which it can be viewed as Suiseki.

Finally, here is an interesting example of Kotaro-ishi. The lower part of the stone has turned white due to erosion caused by weathering, while only part of the upper part shows good quality stone surface. It is interesting to think about how it came to have this appearance.