I didn't say there were verses not describing his mercy but that's what it just is descriptions. We rarely see actual examples of wrath being due to mercy. Most of the Old Testament is destruction/wrath/death.
"Then David said to Gad, "I am in great distress. Let me fall into the hand of the LORD, for his mercy is very great, but do not let me fall into the hand of man."" - 1 Chronicles 21:13
Those who lived during the Old Testament times, in the example given a major contributor to the Old Testament, did not struggle in seeing the mercy of God. This in itself should speak volumes.
God has shown mercy in Genesis, the first chapters as I have already pointed out. Despite Ishmael being sent away, God showed him mercy by blessing him and his descendants. God showed the Israelites mercy by delivering them out of slavery. Despite the Israelites worshipping a golden calf, God still was true to His promise to the Israelites, another display of mercy. God does not change and the descendants of Jacob are not consumed, another display of mercy. God sent prophets to Israel making up for the majority of the Old Testament writings, warning them of destruction if they do not repent and blessings if they repent, another display of mercy. If you read the book of Esther and the books preceding, you also come to realize that God is showing the Jews all throughout the Persian empire mercy by sparing their slaughter, even though the Jews should have been in Jerusalem rebuilding the city. I can keep going on with more examples.
What I feel like is happening here is you are perhaps equating consequences with the lack of mercy.
If someone murders someone in modern times, he or she is sent to prison for a very long time or perhaps given the death penalty. Our justice system doesn't view such a case and dismiss their offense because they say they are sorry and promise they will not do it again. Jesus even spoke on something similar...
"Come to terms quickly with your accuser while you are going with him to court, lest your accuser hand you over to the judge, and the judge to the guard, and you be put in prison. Truly, I say to you, you will never get out until you have paid the last penny." - Matthew 5:25-26
Lastly, I imagine since you say you are a Christian, you believe Jesus is God. If that's the case, remember what Jesus said...
"Jesus said to them, "Truly, truly, I say to you, before Abraham was, I am."" - John 8:58
This alone should help you realize that you have a faulty view on the mercy of God. I'd find it very hard to argue that Jesus was not merciful, which in turns also means, I find it very hard that to argue that God is not merciful. Without God's mercy, there is no such thing as Christianity. By God's mercy, you are called to be a Christian. And remember this, if you don't struggle to find God's mercy in the New Testament, remember that Jesus' birth and what He did fulfilled Old Testament prophecy. So if you believe the Old Testament lacks God's mercy, you are in a very awkward stance.
Some questions I'd like to ask you...if God is not merciful as you have titled the thread, how is it that you are a Christian? Why is it you call yourself a Christian? What even makes someone a Christian?